I have to reboot the routers (I have a time capsule storing the music for sonos as well) and each of the devolos and if i do that everything seems to work.
I haven't been able to narrow down which bits are causing the issue though. Its not the case that things stop working once I switch the devolos on (for example) - everything works for a while, then stops. Sometimes, hours sometimes a day or two later.
Ive set the time capsule to extend the network provided by the Asus router.
Every connection, devolo or timecapsule, has my network name (La Chesnaie) set so i can connect anywhere in the house. That might also be the issue, but again everything works for a few hours or days and then stops working.
OK great, that sounds like a great solution. As you say, if that doesnt work, at least Ill know the problem lies elsewhere.