Try calling your ISP and ask to do a line test. You could be quite far from the exchange and may need a regrade.
Alternatively I would replace filters and router if possible to see if this resolves the problem.
Another possibilty is that a setting on the router may not be ticked, which is to keep your connection up. If this is not ticked you will lose the connection frequently.
To log into the router input your routers ip address into the address bar, type in your username and password(In the routers manual) and have a look around in there.
To find the routers IP open a command prompt, type ipconfig and look for the number next to default gateway. Hope this info helps