Great help from support! They helped resolve the issue, somehow the device got blocked. Going to Insights > Known Clients and select Blocked with the time window with the problem and actually showed...

@Vincent-TP Got an undeliverable message. Total attachment size less than 3MB.

@Vincent-TP Sorry to bother you again, I have the email and replied, but was undeliverable. How do I provide the requested info?

@Vincent-TP Maybe stupid question, but how do I provide feedback to the ticket?

@Vincent-TP I can click on it, but I don't have any filter/block setup. A lock to AP only works when you gave a successful wireless connection. I tried to setup a Deny and an Allow filter, just to...

@Vincent-TP Thanks for your suggestions, but unfortunately it still didn't work. With the logging it showed something interesting, screenshot below. It states that there is a Mac block, mac filter or...