That is odd. I only have 2 installs that include Araknis routers and SONOS. Both only have a few SONOS pieces in them but neither have given me any problems at all. Install times have been a year on one and 3 months on the other.

Despite going thru it with tech support, might want to reach out to a 3rd party to go over your setup with SONOS and the router and see if there is something you are missing.
Has to be something like that or else you got a bunch of defective routers.