Browser in Active Mode Can Stop Pages Loading

I recently installed a new modem/router and tried both Firefox and chrome to access the modem setup via a webpage but after entering user name and password could only get a blank page in Chrome and in Firefox, all it had was Content-Length: 403 . I don't normally use IE but tried it and it worked. As I don't normally use IE, I checked in ESS to see if it was ticked in Active Mode. It wasn't so I ticked it. When I later tried to access the modem webpage in IE, all I got was Content-Length: 403. I then tested all the web browsers and with Active Mode unticked, I could access the modem webpage but with Active Mode ticked, there is only the Content-Length: 403 message.
Does anyone know why this would happen. I have never been blocked from a web page before so don't know if this could affect other web pages and the internet was working ok even though I couldn't access the modem. I am leaving Active Mode ticked but just untick it if I need to access the modem.
I did initially search the web for info on Content-Length: 403 and found it is a common problem so I am not sure if others are using ESS or it is an issue with some firewalls.

 

Hello!

Read the explanation here in the quotes:
https://www.wilderssecurity.com/showpost.php?p=1363104&postcount=2

It seems Active mode is not suitable for the modem cfg page . I'd recommend you generally use passive mode . If you insist on using Active mode , you exclude the page/address of the modem setup so that it is not scanned by the web-access protection . Don't worry , excluding it will pose no security risk for your machine.

 

Thanks very much for the response. I must have missed that thread. I now understand the difference.

 

You are welcome.