random disconection of Era 100 speakers

While it might be tempting, don’t Factory Reset anything without further consult.

Describe your network for us. Model numbers? What is wired? Wireless?

Did you try a simple network refresh? Power down all Sonos, reboot router and controller and power up the Sonos. 

Second thought would be a Wi-Fi issue.

https://support.sonos.com/en-us/article/improve-your-sonos-products-wifi-connection

WiFi setup for system on fiber optic feed. Download speeds routinely 300 mbps, same for upload. 2 pairs are Era 100’s, and one pair is Play 3. I have not done factory reset, but tried rebooting router once. That seemed ineffective. Thanks!

If I were to guess, based on the very brief description, I’d suggest wifi interference , particularly as I haven’t experienced any interruptions when grouping my speakers using the latest version of S2. The minor challenge could be an IP issue, also. Hard to tell. ​@buzz ‘s questions might help pinpoint it. 

Note, rebooting the router often doesn’t do much, unless the Sonos devices are unplugged while it is rebooted. If you leave the devices plugged in, you lose much of the value of rebooting that undefined/unspecified router. A down speed of the router doesn’t say much, we are all more concerned about the local network, between your router and the Sonos devices. 

And just as a precaution, always ‘start’ your grouping with the speaker closest to the router. Nominally, it has the clearest WiFi to ‘get’ the content, and then send it on to other devices. 

Regarding your network let’s get some info. Please answer the questions below

1. Is your network a single router and modem
2. Is your network a router/modem combined into one unit
3. If #2..do you have another router connected to it
4. If neither #’s 1, 2 or 3…Do you have a Mesh network consisting of a main router and 2 or more satellites to extend your network. This would be an out-of-the-box setup by the same manufacturer such as Eero, Tp-link or Orbi to name a few.
5. Are you using a Sonos Bridge or Boost

Speed of the Internet connection rarely matters, Sonos requirements, even for Atmos, are a tiny fraction of most connections capability. My connection is over 500, symmetric, and my system was falling miserably due to local issues. More frustrating everythig else worked fine. Until I resolved the issues with my local network nothing g else helped.