Not sure if this is the appropriate forum to post this but I can't think of anywhere else so here goes: I have an ubuntu 12.04 text only server connecting my home machines, both xp and ubuntu. I registered my domain name with dyndns and set up port forwarding on my router. For months all this was working fine and I was able to use my domain name to log into my home network remotely. Suddenly port 80 ceased working. At home I now have to use my server's ip address to access it while all remote connectivity is lost. Port 10000 which I use for webmin continued working for a while but that's now gone also. I suspect my router but have no clue how to go about establishing that. Any ideas anyone?

One other thing I neglected to mention which might have a bearing: when I issue a call to read an url via my php code it fails regardless of the method. I've tried the DOMDocument and phpQuery methods and both fail. Strangely enough when I paste the same url in my browser it works. I suspect these are two separate issues but I thought I'd mention it just in case.

I assume you mean the Local i.e LAN IP address when you wrote "my servers IP address". Can you still access the servers web pages and webmin from the other computers? If not can you access them from the server itself?

Have you verified if a firewall is running that the you have the appropriate services configured correctly? Have you made changed anything recently on the server? Have you installed any new applications etc recently?

Dyndns dropped their free dns service so if you do not pay then that is why it does not work any more. Your ISP could have started blocking port 80 in addition to other ports.

Everything works fine using the server's local ip address. I've already gone through all your suggestions, first things I checked. No firewall, nothing's changed other than normal updates (ubuntu and xp) to the server and my other machines. As for dyndns their openport tool indicates the block comes from a firewall or the isp. Since I have no firewall it has to be the isp which is comcast. I've already contacted them but have yet to hear from them so we'll see. Meanwhile thanks for the suggestions.

It took specifying an ip address for the network gateway to fix the problem. For some reason I don't understand dhcp stopped working first for port 80 and eventually altogether. Everything now is back to normal but I'd sure like to know why it stopped working.