@Grandy I'm having the same problem. Started about 2 weeks ago. All my Apple devices (Macbook Air, Macbook Pro, iPhone 12 Mini, iPhone 12 Pro) have difficulty connecting.
If I reset the Deco's, they'll connect to my Apple devices fine for 24-48 hours. Then trouble rejoining.
Kindle devices and TV's are fine. And haven't had any issues. Deco m5 is fully updated, running on an ethernet backbone.
Everything worked fine for about 1 year, until the past 2 weeks.
Any solutions? I contacted TP-Link Tech SUpport - they're insistent its a settings issue on my device, and want to VPN and do a remote session. However, I'm uncomfortable with that and furthermore, 4 devices all suddenly having a setting issue? Seems more of a Deco issue since connectivity resolves with rebooting the Deco.