I used to have a pair of Deco M9 Plus that worked perfectly with all my legacy 2.5 mhz band Airplay speakers (B&W A5) for the last 2 years.

Some months ago I added a Deco X20-DSL, replacing the previous M9 as the main Deco, and relocating the M9 to wireless outdoor deck location.  Ever since then I have unreliable connections to all my legacy 2.5 band airplay speakers.  Sometimes they work ok for days, other times they drop in and out from anywhere between 20 seconds and minutes at a time.  One speaker is only 4' from the main X20-DSL,  another is only 2' from a Ethernet connected M9.  Many times the audio source is Ethernet connected. I've tried disabling the mesh technology for these devices, and it has made no improvement. I've also tried resetting them and re-establishing the network connections.

Is there some compatibility issues here caused by the newer Deco X20?