TIVO Desktop doesn't see my DVRs

I have been using Tivo Desktop for awhile but about 6 months ago it stopped seeing my DVRs. I don't think I did anything with any of my settings. Today I spent most of the day on the telephone with Tivo and cleaned and reinstalled the software, changed from Bonjour to Beacon and back again. I still don't see anything. Any suggestions? I am not terribly sophisticated with computers or routers.
Thanks.