I had almost forgotten that my internet provider has a domain called .local exposed on it's dns servers.
this screws up name resolution between linux and windows machines via samba which use a .local domain and expect it to be.... duh local.
I change my dns server on the network interface to the google public dns 8.8.8.8 and 8.8.4.4 as the alternate, and the problem magically disappears.
This doesnt seem to be well documented on the interwebs, but came to light a year or so ago when I switched internet providers, and my office lan blew up so to speak.
worked with the internet disabled, wouldnt work and resolve names with the internet on...
Thought I would bump this subject, because it took a lot of hours to figure out, and the references are buried deep in the web.
See Avahi and .local domain for more reading on the subject.
Mediacom was able to give me some addresses to plug into my router that didnt do this but obviously it didnt stick because the problem showed up again
