I'm with Plusnet on fibre and I have their standard router. The internet connection is absolutely fine, fast and stable, but my home network is annoyingly unstable.
A WiFi printer, Sonos speakers, Windows Homegroup and even just sharing iTunes files between devices with Home Sharing are routinely dropped and usually its only re-booting the router that resolves the issue until the next time it happens, which is usually within several days.
Plusnet did replace the router once already but it's been no better. Is a better router likely to solve the problem (I'm think about something new around the £100-120 mark) or this just a fact of life with different devices all connected to the same network?