Hi Speculator,
Maybe you should use 2 ADSL connections...there are routers which use the second connection in case the first one is dead. Instead of this kind of router you can also adapt a PC with Linux as a operating system. With some programming skills you can manage the connections almost the same way as router although not that efficient. The other solution is to change ISP. Both are not cheap. Or... as you 've mentioned - you can make a test with two computers...one with
fx software installed and second without it (same ISP)... you should also consider to make a test with two different ISPs.
Your connection crash is probably ISP dependent. It can also happen that DNS (Domain Name Server) is not working and not solving web addresses to IPs...causing 'connection crash' (web sites do not open etc.)
Cheers,
Running Turtle