NAT issues and other oddities

**Studio1** · 21-03-08, 09:44 PM

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** · 30-03-08, 06:34 PM

... 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 ... IBM United States - 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 http://128.42.18.103 - 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 :-)

21-03-08, 09:44 PM	#1 (permalink)
Studio1 Senior Member iTrader: (0) Join Date: Jan 2008 Location: Inside the toaster Posts: 540 Spent time on board: 4 Days and 3:47:18	Router issues and other oddities 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? Last edited by Studio1 : 21-03-08 at 10:19 PM.

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30-03-08, 06:34 PM	#2 (permalink)
eyesee Senior Member iTrader: (1) Join Date: Mar 2008 Posts: 141 Spent time on board: -	... 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 ... IBM United States - 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 http://128.42.18.103 - 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 :-)