Beginner here. I had a friend configure my network using CAPsMAN about 4 years ago, but there are problems now and friend is unavailable to help. I do not have the knowledge to diagnose or remedy.
Problem is devices such as mobile phones, etc are having difficulty accessing the internet due to frequent connection drops.
The log from router is attached. There seem to be a lot of items that I do not think are normal.

Is someone able to interpret the log and suggest a remedy or see an issue?

Otherwise, perhaps I wipe everything and start from scratch (but I realize this may be a big task I'm not sure if I can tackle and I have a lot of configuration I want to not have to redo such as connected NAS, various backup and synchronization schemas running internally)?

This is my network topology, blue lines are wired ethernet connections.

"registered to other interface" ... happens indeed very often (this is "wifi roaming") when you have wifi interfaces with the same SSID. The client device decides on its own, when to roam.

"disconnected, received deauth: sending station leaving (3)" often comes when the client device cannot communicate with the internet. Most clients have a built-in test URL
The reason here often is because the client has the wrong IP address, gateway, DNS server set. Typical happens when the correct DHCP could not offer the correct DHCP lease.

"disconnected, received disassoc: sending station leaving (8)" is also again the client giving up on this connection, because no internet access

Deauth and dissassoc information comes from the client device.

Thank you for your response. If I'm reading correctly, most or all of these "newer" issues are NOT due to trouble with configuration, but mainly client related?

I've attached my compact configuration if someone can see problematic settings.

Also, is there any sense in upgrading RouterOS v7.x?