I have LAN of two computers, connected to the internet through Motorola SB5101 modem and WRT120N router. On the lower right corner of the screen appeared icon with two computers and red cross between them and message in box "Local area connection: a network cable is unplugged" and the orange "PC/Activity" light on the modem - which is normally flickering - goes out for a few seconds. The error message stays on screen for one or two seconds, then red cross between computers switch to little golden one, message gone and after two to four seconds connection restored. Sometimes it happened two times immediately one after another.
I consequently connected each computer directly to modem and such behavior desappeared. So please - help me resolve this issue. This may happen during the process of sending e-mail or performing some other activity, and break it. So it is quite serious issue to me.
Your help is highly appreciated.