issues with dropping connection?

[#1]

HI, for a maybe 5 weeks now, at random the connection is lost from one of our computer (2 laptops and a desktop connected 24/7) sometimes only 1 computer stays online.  the only way to get the other back online is to turn the router on and off again. although this is annoying when it happens often i worry more about our connection being marked as 'unstable' and our speeds reduced (currently struggling to get up to 80kbs anyway).
Is there any other possible sollutions other than on/off or is that what we shoudl stick to doing.
Fyi, routers in master socket, filters used, firewalls fine, using cable not wireless.
Much appreciated.
Rob

[#2]

Looking at your previous post I suspect that something is badly adrift.
Can you provide your Router Stats - speeds, noise margin and attenuation both up and down
Then can you connect the router to the test socket (behind the master socket) with nothing else plugged in and report the stats again