Comcast issues or hardware issues?

Discussion in 'hardware' started by GideonD, Oct 4, 2010.

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  1. GideonD

    GideonD Registered Member

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    Everyday this past week I turn my computer on at about 6AM and I have no internet connection. I leave it for 5 - 10 minutes and the connection finally picks up. Sunday I turned it on for the first time at 11:30AM and the same problem occurred. I turned other PCs on at the same time and they also have no connection so I know it isn't a specific computer. Once the connection picks up it's fine the rest of the day as long as a computer is on. When I turn all computers off for an extended period (a few hours) the connection problem occurs again. I have a Scientific Atlanta modem from Comcast and a hardwired SMC router with another wireless Linksys WRT54GL chained to that. Tonight I plan to pull the routers out of the array and connect the modem directly to my computer so I can see if the problem still occurs tomorrow morning. If it does then I can rule out the routers. Does this sound like a modem/router issue or an ISP issue?
     
  2. YeOldeStonecat

    YeOldeStonecat Registered Member

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    What are you plugging the PCs into? The Linksys or the SMC? Double NAT'd?
    How is the Linksys connected to the SMC?
    What model SMC router?

    Rethinking, why not remove the SMC from the mix? Power off your cable modem (the sci atlantic)
    Assuming that your Linksys is running in default mode as a router (meaning, you didn't reconfigure it to run in access point mode), uplink the WAN/Internet port of the Linksys to your sci atl modem. Power on the Linksys, power up the modem...allow the modem to "synch" (can take a minute or two)..once synched, now power cycle your Linksys router. Now go ahead and boot up a PC that is plugged into one of the LAN ports of your Linksys.
     
    Last edited: Oct 4, 2010
  3. GideonD

    GideonD Registered Member

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    The SMC is the primary router. The Linksys was added to extend the network into the wireless realm. WRT54GL is connected via a LAN port, not a WAN. This was carefully configured with a lot of research to avoid common issues that occur when trying to do this. DHCP is only enabled on the SMC. I don't recall for certain about the NAT setting until I can look again. This setup has been working well for a couple years now. The computers that I'm certain have had this issue are all connected directly to the SMC. I doubt there is any issues with the Linksys at this point but I won't rule it out. The SMC is getting close to 10 years old now so it may be on it's last leg. I think its a SMC7004VBR. The SMC is running stock firmware and the Linksys is running Tomato.

    If a direct connection to the modem works fine in the morning, I'll assume the issue is with one of the routers and start testing them per your suggestions.
     
  4. GideonD

    GideonD Registered Member

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    Same issues this morning directly to the modem. I might get them to swap it out to make sure that is the problem before I buy my own. The connection stayed out even longer this morning. Last night I turned it on after 10 hours of no internet usage and it worked just fine. The odd part is that when I get a connection, it's solid. There are no sporadic drops. When I've had modem problems in the past the connection would cut out periodically. In this case, it's just in the morning and seems to work fine once the connection is established. I'm betting it's service related.
     
  5. YeOldeStonecat

    YeOldeStonecat Registered Member

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    Ahh OK, so you did configure the Linksys as an access point. Just to check, (although I'm sure you did since it's been running for years)...the Linksys has a different LAN IP address than the SMC? Linksys defaults to 192.168.1.1, and I think that older SMC defaulted to 192.168.2.1. Comcast uses an SMC combo modem/router for their business accounts that uses 10.1.10.1.

    Anyways, yes that model SMC is old and slow, and since Comcast introduced Powerboost to most of its covered areas, you more than likely live in and area that has that higher speed service and the SMC would be a bottleneck for you, it's not able to keep up with the faster bursting speeds of PowerBoost. I would definitely "retire" the SMC.

    Even though the wrt54gl is also old by todays standards, it's still much faster than the SMC (the wrt54gl can hang to about 50 megs of throughput). Plus you're running Tomato on it..which is great firmware, those units are rock solid stable with Tomato.

    "A chain is only as strong as its weakest link". ;) If you need more LAN ports (you have more than 4x computers that need to plug in)..just add a little switch.

    OK back to your problem....at first I think I mis-interpreted your bad connection to be on the LAN side, which is why I wanted to examine that more closely. Your added post about the same thing happening when connected directly to the modem seems to point that your issue is indeed on the WAN side..perhaps the cable from the street into your house, through splitters (the usual culprit)..up to where your modem and router are located.

    The next time you fire up your computer, and you don't have internet...can you access the web admin of your router? If so, this shows that your LAN is fine..your PC can connect up to the router fine, but you're not actually getting past the router out to the internet. So lets further check to see what part of the connection is failing...as sometimes it's just DNS related. When you cannot connect to the internet, while logged into your primary routers web interface, check the status section. If the router cannot pull a good public IP from your cable ISP, you'll see 0.0.0.0. ..and sometimes 192.168.100.something. If it has a good public IP, you'll see something like 64.65.124.12. Regardless of what you see, there's usually a button on your routers web admin WAN section to "renew" or "release" and "renew", or something similar. Click that. See if it pulls a new IP. Once (or if) it gets a new IP, can you connect?

    If it gets a new IP but you cannot connect, lets further test connectivity...run a ping to www.google.com. Any replies? If no, lets test a ping via IP only. Ping 208.67.222.222. Any replies? If no, there is a connection issue, if yes, than you may have a DNS configuration issue and we can look more closely in that area.

    Assuming you have a connection issue, the most common cause of cable ISP connection issues I run into are related to "splitters". Those are the little devices that take a single coax line and split it into one or more lines, like if you have several TVs in the house. They fail..and they fail at quite a frequent rate, especially if they're located outside or in a basement with a damp environment.

    A quick fix. Power off the modem for at least a minute. Disconnect the coax on it. And disconnect any/all splitters between your modem, and where the coax comes into your house. Reconnect. Power up modem, allow to synch, and then power up router. Reboot (or release/renew IP) PC. Test.

    The best way to run coax and splitters in your house, with a cable modem, is to have your cable modem be on the first splitter closest to the street...and your TVs after that. Meaning, the line comes into your house from the street..you want a 2 way splitter only....you make that first split go to your cable modem on one half of it, and the other half goes to your TV..or another splitter which then splits up to each PC. This way your cable modem gets the strongest, cleanest signal. You do not want your cable modem behind multiple splitters...you want it on the first ..most outside one.

    Coax splitters are inexpensive. You can pick up replacement ones at your favorite electronics supply store, or...your ISPs local office will often hand you some for free if you walk in and ask.
     
  6. GideonD

    GideonD Registered Member

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    Ahh OK, so you did configure the Linksys as an access point. Just to check, (although I'm sure you did since it's been running for years)...the Linksys has a different LAN IP address than the SMC? Linksys defaults to 192.168.1.1, and I think that older SMC defaulted to 192.168.2.1. Comcast uses an SMC combo modem/router for their business accounts that uses 10.1.10.1.

    Yes each one has it's own IP. I can access each interface separately.

    Anyways, yes that model SMC is old and slow, and since Comcast introduced Powerboost to most of its covered areas, you more than likely live in and area that has that higher speed service and the SMC would be a bottleneck for you, it's not able to keep up with the faster bursting speeds of PowerBoost. I would definitely "retire" the SMC.

    Actually, I've done speed testing periodically ever since getting Broadband and each time Comcast increases speed the SMC seems to handle it fine.

    Even though the wrt54gl is also old by todays standards, it's still much faster than the SMC (the wrt54gl can hang to about 50 megs of throughput). Plus you're running Tomato on it..which is great firmware, those units are rock solid stable with Tomato.

    I've mainly kept the SMC inline because I've had issues in the past with Linksys and P2P stability. If Tomato resolves this I can remove the SMC from the chain.

    "A chain is only as strong as its weakest link". ;) If you need more LAN ports (you have more than 4x computers that need to plug in)..just add a little switch.

    OK back to your problem....at first I think I mis-interpreted your bad connection to be on the LAN side, which is why I wanted to examine that more closely. Your added post about the same thing happening when connected directly to the modem seems to point that your issue is indeed on the WAN side..perhaps the cable from the street into your house, through splitters (the usual culprit)..up to where your modem and router are located.

    The next time you fire up your computer, and you don't have internet...can you access the web admin of your router? If so, this shows that your LAN is fine..your PC can connect up to the router fine, but you're not actually getting past the router out to the internet. So lets further check to see what part of the connection is failing...as sometimes it's just DNS related. When you cannot connect to the internet, while logged into your primary routers web interface, check the status section. If the router cannot pull a good public IP from your cable ISP, you'll see 0.0.0.0. ..and sometimes 192.168.100.something. If it has a good public IP, you'll see something like 64.65.124.12. Regardless of what you see, there's usually a button on your routers web admin WAN section to "renew" or "release" and "renew", or something similar. Click that. See if it pulls a new IP. Once (or if) it gets a new IP, can you connect?

    If it gets a new IP but you cannot connect, lets further test connectivity...run a ping to www.google.com. Any replies? If no, lets test a ping via IP only. Ping 208.67.222.222. Any replies? If no, there is a connection issue, if yes, than you may have a DNS configuration issue and we can look more closely in that area.

    Assuming you have a connection issue, the most common cause of cable ISP connection issues I run into are related to "splitters". Those are the little devices that take a single coax line and split it into one or more lines, like if you have several TVs in the house. They fail..and they fail at quite a frequent rate, especially if they're located outside or in a basement with a damp environment.

    A quick fix. Power off the modem for at least a minute. Disconnect the coax on it. And disconnect any/all splitters between your modem, and where the coax comes into your house. Reconnect. Power up modem, allow to synch, and then power up router. Reboot (or release/renew IP) PC. Test.

    The best way to run coax and splitters in your house, with a cable modem, is to have your cable modem be on the first splitter closest to the street...and your TVs after that. Meaning, the line comes into your house from the street..you want a 2 way splitter only....you make that first split go to your cable modem on one half of it, and the other half goes to your TV..or another splitter which then splits up to each PC. This way your cable modem gets the strongest, cleanest signal. You do not want your cable modem behind multiple splitters...you want it on the first ..most outside one.

    Coax splitters are inexpensive. You can pick up replacement ones at your favorite electronics supply store, or...your ISPs local office will often hand you some for free if you walk in and ask.

    I'll give some of this a try the next time I have time when the problem occurs. I have new cabling up to the house. It was replaced a few years back by Comcast when they bought out Adelphia. The modem is connected to the first splitter via new cable as well. All cable up to the modem was provided by Comcast as was the splitter.

    I've been told Comcast is upgrading the network in nearby areas to DOCSIS 3.0. I'm wondering if there may be some work going on that could be causing all my issues.
     
  7. YeOldeStonecat

    YeOldeStonecat Registered Member

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    What are you benchmarking your speeds at? A quick Google check shows that model SMC peaking at about 11 megs of throughput, with SPI off. Comcasts powerboost should have you at a minimum of 16 megs, when I had it I was usually in the high 20's/low 30's. When they first started with powerboost I was actually in the 70 meg range for a while, but then when they started fine tuning their settings, ~30 megs day to day.
     
  8. GideonD

    GideonD Registered Member

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    I have the 12 meg service called the Performance package and the last I did a speed test at speakeasy it was reading around 20 megs. I'll check it again tonight. Powerboost has made an accurate speed test almost impossible. I know that when I ran a fully unthrottled torrent download on a linux distro I was getting about 700 down on a wireless connection in my old linux rig.
     
    Last edited: Oct 5, 2010
  9. YeOldeStonecat

    YeOldeStonecat Registered Member

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  10. GideonD

    GideonD Registered Member

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    I've never used QoS functions before but would certainly be interested in taking a look at them.

    Tonight I had no connection at all again. I also had no luck logging in to the routers. Finally, I uninstalled Comodo, just to be safe, then I swapped out my routers. The Linksys is fully configured as the only router now. All my settings are back in place. Now all seems smooth for the moment so I'll wait and see how things go for the next few days. Then I'll think about getting my own DOCSIS 3.0 Modem and ditching the lease fee from Comcast.
     
  11. GideonD

    GideonD Registered Member

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    So far so good this morning. Immediate connection. Hopefully it was just the old SMC gasping it's last breath.
     
  12. YeOldeStonecat

    YeOldeStonecat Registered Member

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    Sounds good.
    You'll find some pre-canned QoS settings in Tomato that may help you.
    And try to get a Motorola modem if you shop for a Docsis 3 one. Getting your own modem is quite easy with Comcast. Write down its MAC address..and double check that you got it accurate. Plug it in, power it up, naturally you will not be able to surf the internet, you'll be stuck in Comcasts wallgarden (registration intrAnet). Just ignore that, call up Comcast support, tell them you just got a new modem, read them the make, model, support will ask you the MAC address of the modem, read it to them, they'll find it and upload a config file (provision it), a minute later it will reboot. Now connect your router, fire up the router, fire up your PC, and you should be online. All said 'n done in about 10 maybe 15 minutes.
     
  13. YeOldeStonecat

    YeOldeStonecat Registered Member

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    And don't forget to post some speedtest results afterwards.
     
  14. GideonD

    GideonD Registered Member

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    Thanks for all tlhe help. I'll definitely check speeds when I eventually get that modem.
     
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