Hi, I'm not a developer or programmer or techie, just someone who uses 3 computers in my business. I had the same problem at one point. I have basically the same setup and equipment as you (and number of computers, we'll call them Main, Second and Third) After months of frustration I found it was a third-party firewall that continually created problems with my network. So I uninstalled it (and actually never used it again, because it gave me nothing...