first guess would be internet settings (since you changed the router etc. you may have reset your ethernet/wireless connection properties as well. Check firewall settings on your computer (as many OS's will reset the firewall when a change in your ethernet happens (as will happen with a new router many times). The issue may or may not be in your router firewall or DHCP settings as well. I am not an expert but those are the first 2 places I would check if I knew I was not even connecting to the server, and I could close and restart and it will come up ok for a bit. Check to see if your Browsers are defaulting to auto-detect internet settings (or the like). This would cause it to slow down anyway as it will try to detect the internet settings (or proxy) every time it reloads.
