Merged the two networks (apple extreme, Deco M5) into one (Deco5), looks like there was interference or an auto select feature that kicked in when Deco M5 signal was unstable, I'm guessing here,...

@Jubilado got it figured out, wi-fi interference, issue resolved! Thanks for getting back to me!

One of the wireless connected Deco5M keeps on dropping out, not having this problem with the Deco 5M connected to the Router or the other wireless connected M5 unit. The Deco 5M that keeps on...