I've seen similar threads with no real fix and it seems to be an issue across different Deco Mesh hardware options.

I bought the XE5300 from Costco.  I bought two 3-packs as I have a large-ish home, but also wired well, so it's setup with one primary and 5 satellites all on a wired backhaul (1 GB).

Internet is 1GB fiber.

I'm fairly technical so have done a bit of trouble-shooting with no success in finding a real fix that lasts more than a few hours... 

The problem: I've had issues with various iPhones, iPads, iMac and some HopePods get dropped and fail to log back into the network.  
When logging back in it will say, "Invalid Password" even though, 100% it's not invalid.  The only fix I've found is to reboot the Decos.  This will fix it for a while.

Rebooting the Apple device... even doing a forget network and/or resetting network settings in iOS does not fix it.  It appears to be a Deco-side issue not Apple.

What's crazy is my iMac is wired and has wifi so that it can do AirDrop etc. and I've had the wired stay hooked up just fine, but cannot reconnect wifi at times!  

My setup is both the 2.4 & 5Ghz ... and 6Ghz SSIDs are the same so the device can select.  My newer devices usually join the 6Ghz but will move well to the slower options when needed.  
I have a decent amount of Echo devices a few Nest Devices, and some other random things that are also connected.  I've had challenges with an Echo dot or two at times, but more often than not, my devices with this is problem is an Apple product, but definitely not limited to Apple hardware.

I do not have an IoT network setup, but considering it.  

I know I'm not alone, but haven't foudn a solution.  HELP!  Don't want to return these, but am getting very close and going with another brand like Netgear etc.