ADSL filter problem/home network

Glenzeke

Just moved from Plusnet to Tesco (cheaper with unlimited download & anytime calls). Supplied TG580 router keeps dropping connection.
Tried using their ADSL filters:
1. Lost phone connection completely
2. Very poor internet connection
Replaced previous filters and back to status quo.
Will see if router settles down before digging out an old router and programming it.
Admittedly using router on an extension, but had no problems with o2 and plusnet in previous years.
So, not happy with supplied Tesco hardware so far...