Here are some AirPlay details. Note that you cannot AirPlay to the 100’s when they are used as surrounds.

Thank you for your response. I’m aware of this, however, I’m using the 100s as a stereo pair. 
 

Seems odd. What are you sending the AirPlay 2 signal from? Have you called Sonos Support to discuss it?

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

Oh. Should have reread the OP. 

It’s been years since I ran into issues, but they weren’t Era 100s. But I did have to reboot my iPad and/or iPhone when it occurred. I’d want to try rebooting the router, just in case, as well. 

You’ve mentioned Era 100’s in stereo pair. You also mentioned Beam connected to your TV. Then you mention issue with Family Room. 

Questions:

• Are you having Airplay issues with the Era 100’S and the Beam over just one or the other?
• What speakers are listed as Family Room and is that where the Airplay issue lies?

Beam is connected to the LG TV. The 100s are stand alone in the same room and for convenience I’ve designated them as being in the Family Room and the beam in the TV room. Have no issues with the Beam and the TV. I also have a Sonos One SL in a separate room and that airplays successfully as does the Beam. 

It does seem odd. But you haven’t responded to my question. What did Sonos support say when you called in? Did you supply them with a system diagnostic ? What have you rebooted?

Waiting to contact them today. I’m in Australia and it’s Monday. Let you know what they have to say.

Make sure that the Era100’s aren’t in Bluetooth mode. If they aren’t I’d remove them as a stereo pair and set them up again.

Note:

Upon removing them as a stereo pair they should revert to individual rooms as they should have been before you paired them as a stereo pair. If they don’t revert back to separate rooms you need to factory reset them. After the factory reset set them up as rooms with distinct names like Era 0ne and Era Two. Then select a room (Era One) to start the stereo pair setup.

If you’d rather not perform a factory reset (as it will erase any data that may be useful to Sonos Tech support) then by all means follow the advice of ​@Airgetlam .

Thanks. Not in Bluetooth mode. Rebooted the ones and the beam. No changes. About to contact Sonos. Cheers. 

 ​@arthron check your Home app on your iOS device. Make sure your eras are listed there as the same name they appear in the Sonos app. IIRC if they are not the same airplay will not work. 

Thanks everyone. I’ve been in contact with Sonos support. Carried out diagnostics, rebooted etc to no avail. Sonos has offered to replace the speakers and I have sent them back and waiting for the replacements to be shipped. Hoping the new ones will work, gut not overly confident as I believe there is a conflict with the Beam/LG Oled TV and the Era 100s.