Hard to tell from the description, all ‘anecdotal’ reports are rife with potential misunderstandings, due to not enough ‘hard’ data. I’d be looking at two potential issues. The first is relatively ‘simple’ wifi interference . There are a lot of suggestions to look at in that linked FAQ.

Less likely, but also possible, is a duplicate IP address issue, exposed when Sonos reboots their product during a software update, and the router is in an unusual state. I would definitely try a network refresh, by unplugging your Sonos devices from power, then rebooting your router, refreshing its tables. Wait a couple of. Minutes before plugging back in your Sonos devices. Unfortunately, most routers don’t have a way of detecting, or showing duplicate IP addresses, most of them just show what is connected at the moment the report is run. 

However, if the issue continues, I would  recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

@cap3344 

I‘m not surprised that you are running into grouping issues with a Play3. Imo it has got very old hardware and shouldn’t be S2 supported. To increase wifi stability on group use you can try to set a higher delay than 75ms on ports input settings for group playback. 

I have my stereo’s tape loop out sent to my Port’s Line-In, and I use it to send the phono input around the house.

I hadn’t used it since the “upgrade debacle” earlier in the year, and wow, it’s unusable now. It sounds like a bad cell phone connection, even when sent to other wired Sonos speakers.

It used to work flawlessly at 75ms. Higher latencies are not an acceptable solution.

My network is impeccable, and hasn’t changed. I’ve rebooted everything.

Such a disappointment.

@speedycatcatcat 

I would understand if there are issues with network performance, but not with sound quality. If input level wasn’t changed and everything is ok with cables and hardware, why should sound quality be affected? 
Did I get it right… there are no drops but just poor sound quality?

I changed the delay and source level settings and did a quick side by side check with the Move and Play:3 (not grouped) and both played fine. We’ll have to see the next time it’s a “must have” situation.

@Schlumpf 

There are drops.

I likened it to a bad mobile phone call as an example.

Ok, I understand… If using a higher delay is no option, the only other thing that can be done on settings is „audiocompression“ set fixed to „compressed“. 
Besides that imo there is just left optimizing the network. There also could be new interferences coming from the neighborhood that were not there in the past. So changing fixed wifi channels imo always can be an option.