Always have to reset my router to use Sonos app/control

Most of us don't have any issues from one year to the next. Obviously we don't know anything about your network, but there is something peculiar with your network.

I recently moved and I don't have complete control of the network. In my case there are two separate WiFi networks and one does not work very well. I'm not the network administrator (yet -- we'll fix that over the weekend) and my SONOS system is on the not so good network. One issue that I have (and this could be similar to your issue) is that I have both networks defined for my pad and phone and sometimes the phone or pad will sign-on to the wrong network. When this is the case I cannot control the SONOS system. The controller will complain that it cannot find a SONOS system. It's a simple fix. All I need to do is force the pad or phone to use the correct network. For a SONOS system, the controllers (phone/pad) and the players must be on the same network. In a few cases similar to yours it was discovered that the phone/pad was signing on to a neighbor's WiFi. In this case, Internet access will be fine, websites will work, services will stream -- but you will not be able to control the SONOS system.

Again, we don't know anything about your network, but if you need to regularly restart the router and it is correctly setup, the router needs to be replaced.Years ago, I had an ISP supplied router that was totally unreliable. There were legions of online complaints about this device. I had to fully restart my network about once a month. Finally, I was able to replace that router and my network issues were resolved permanently.

Describe your network for us (give model numbers). We may be able to help.

I agree with @buzz. There is one experiment you could do that would help in troubleshooting. Could you connect one Sonos device to your router by Ethernet and see if the problem continues to arise? Whatever the answer, it will help to rule a few things out or in.

If I had a £/$ for everyone who has said it cannot be their network because everything else works - yet it turned out to be their network - I'd be a wealthy man. OK, that's an exaggeration, but I'd say that when such problems have arisen it was about 99% local network/router related, 0.9% faulty Sonos device, and 0.1% general Sonos bug.

Whilst @buzz describes his issues with two different WiFi networks, a very similar thing can also occur with WiFi repeaters, or extenders, about the place operating on different WiFi channels to the main router, or by use of a routers 'guest' WiFi network. So, if present, I would at least switch off those things temporarily, at least whilst testing the Sonos system.

You may also find that 'fixing' your Sonos IP addresses using the routers DHCP Reservation Table and fixing your mobile controllers IP address, may help to address any router iP leasing issues.

Going to static / reserved IP addresses and Boost (wired to the router) mode ended my Sonos issues. It also lets me use the full capabilities of my WiFi hardware without having to limit it to what Sonos can support.