my internet connection on my iMac (wi-fi) continually cuts out. I am running a Base Station

my internet connection on my iMac (wi-fi) continually cuts out. I am running a Base Station and router. Randomly the connection times out - the ISP, Internet and Server selections turn amber - the rest remain green.

To remedy I run Network Diagnostics and it fixes. But this is now becoming a common theme - every 5 - 10 minutes.

None of the other devices (phones / Mac Pro) running off this Base Station seem to have a problem - ONLY the IMac

HELP??