My dom0 is only responding to the network some of the time, as evidenced by how stuttery it munin graphs are for the last 36 hours or so, and the fact it took 4 tries before I could ssh into it. Meanwhile, the domU which relies on the dom0 for network bridging, is going just fine with no evidence of network problems.
Just in case, I’ve set up an “at” job to reboot the dom0 at 9:45. I’ll kill the job if I can figure out what is making it flaky in the mean time, but because it’s an at job it will continue even if I manage to totally pooch the network while I’m working. Cross your fingers and hope it comes up again.