[xubuntu-users] networking

[Bill]

Greetings. For so long as I've used *nix and *ubuntu (over a decade) I 
should know the answer to this question, but for all of my hours of 
searching for an answer I can not seem to diagnose my problem. I hate to 
burden the list with something so simple, but I've run out of patience.

I have a home network consisting of a desktop, laptop and dsl 
modem/router. I'm running xubuntu 12.04 on both computers (Linux 
xxxx-xxx-xxxxx 3.2.0-39-generic-pae #62-Ubuntu SMP Wed Feb 27 22:25:11 
UTC 2013 i686 i686 i386 GNU/Linux). Everything worked without a flaw 
until I had to reset the router following an isp (CenturyLink) problem.

Now I can connect to the internet, and ping the gateway from both 
computers, but can not ssh or rsync or ping from one computer to the 
other. (However, I can telnet to port 22.) Attempts to connect yield 
"Destination Host Unreachable". So far as I can tell, all software and 
hardware necessary to doing so are installed and working properly.

I have disabled and re-enabled all firewalls and iptables to no avail. 
I've run all of the commands I can find to diagnose the problem  (e.g., 
ifconfig, route, traceroute, nslookup, iptables-save, nmap, netstat, 
dhclient, iwconfig, etc.).

It must be something so simple that I am overlooking it; I had it set up 
and it worked... I also played with the router configuration (port 
forwarding to port 22 on both machines, changing the default server, 
etc.). I do not recall having this difficulty in getting the two 
machines to talk to one another in the past.

My thought is that perhaps through the many updates that have been made 
since the release of 12.04 something of which I was unaware in the 
networking configuration has changed (both machines dual boot to Ubuntu 
12.04, and I have the same problem in it)?

Thanks for your help.