Not sure my electronic skills are up to the kind of mods needed

As for the drop-outs, are you using a wireless network? Try re-orienting your aerials. Keep wires and other obstacles away from the aerials. Since doing this I have had no problems. Signal strength is not the whole story. It won't tell you if you are suffering from interference.

I assume that if using WiFi, you are using a non-overlapping channel. The only ones that don't overlap are 1, 6 and 11. In other words you have to jump five channels to get to one with no overlap. Have a scan to see what your neighbours are using (if any).