NAT issues and other oddities

[BCNZ]

I am on ADSL and have a modem/router which has one LAN port. This feeds a 4 port switch that feeds my 3 computers.
No problems there.

Every now and then, I am working away on my internet machine (usually chatting to someone on an IM program) and I find that my access to the web just stops. Trying to get to any webpage is impossible.
Yet, the IM program continues to run Ok, as do any P2P programs or FTP downloads I may have going.

So, I have come to the conclusion there is an issue with http requests.

The way I solve this incidentally is to simply reboot the modem. Then everything starts working again.

My thoughts are that it is something to do with the router. I have noticed that when I have the http issue on my internet computer, if I try to access web pages on any of the other computers that are connected to this system, they have the same problem - ie can't access any pages.

Can someone explain, confirm or deny whether it is a router issue, how common this is, what causes it (is it caused by dodgy packets?) and is there a solution to the problem?

[eyesee]

... without going into great detail ... it sounds like a DNS problem ...

Check to see if you are able to access a known site - when this problem occurs - by pyping the site IP directly into your browser ...

For example ... - if you type this URL - you will go to the IBM US site

When you have your problem - try above URL again ... according to your info this will not work. If you have a DNS problem , then by typing - you will be trying to connect to same site - but without needing to access a DNS server.

If this works - then you most certainly are loosing DNS when you problem occurs. This explains why your other applications are still active - because they don't rely on maintaining DNS resolutions ...

OK, if its DNS ... then we have some focus as to what to look for in your router configuration. Yes, this could be just a router missconfiguration.

Perhaps when you confirm that above ... you can also specify your router make and model and settings you used for the DNS set-up with your ISP (check with them first - as they may have given you incorrect info in the first place).

Hope this info is helpful :-)

[evilbrian]

I have been having exactly the same problem with one of my office PCs since late on Tuesday March 31. I have no problem connecting to limewire, torrent sites or messenger....in other words, any PtoP service, but none of my browsers will open. Also have no problem seeing and interacting with any other PC in the office network

It's a Dell, and their annoying network assistant now comes on every 60 seconds (which in itself indicates a problem), only to do an 'analysis' and tell me that it's working OK. Trend Micro, on the other hand tells me correctly that I'm not connected to the Internet. Have turned the Trend Micro firewall off but that has no effect. Tried eyesee's suggestion of typing the numerical addy but that had no effect either. Am on Optus Cable in Melbournes SE Suburbs, and all otehr PCs in the network can access the internet just fine.

Any suggestions gratefully received.

[BCNZ]

... without going into great detail ... it sounds like a DNS problem ...

Check to see if you are able to access a known site - when this problem occurs - by pyping the site IP directly into your browser ...

For example ... - if you type this URL - you will go to the IBM US site

When you have your problem - try above URL again ... according to your info this will not work. If you have a DNS problem , then by typing - you will be trying to connect to same site - but without needing to access a DNS server.

If this works - then you most certainly are loosing DNS when you problem occurs. This explains why your other applications are still active - because they don't rely on maintaining DNS resolutions ...

OK, if its DNS ... then we have some focus as to what to look for in your router configuration. Yes, this could be just a router missconfiguration.

Perhaps when you confirm that above ... you can also specify your router make and model and settings you used for the DNS set-up with your ISP (check with them first - as they may have given you incorrect info in the first place).

Hope this info is helpful :-)

Thanks Eyesee, only just found your reply! LOL

The problem continues, so when it happens again I'll try your suggestions and see what happens, then report back.

Thanks.