@Guy-26 

You can upgrade the firmware to the latest version to have a try. 

What's the IP of your EAP and Omada Controller? And do you connect your Controller host via an ethernet cable?

From the information, we can know that the EAP is disconnected from the Omada Controller. You can connect your Controller host to the router/switch via an cable, it will be very stable. 

@cbq Thanks for the response :-)

Yeah, i'm updating to the latest firmware today. But the thing is that it is a problem we have had for many months. 

And I do connect my Laptop (where the Omada Controller is installed) through Ethernet cable when it is in the office. But is rare it is in the office.

@Guy-26 

Normally TP-Link will add some new features and fix some bugs in the new firmware. You can check if the problem still exsits after you upgrade the firmware.

You set statistic IP for the EAP, do you set DHCP Reservation for the EAPs on the DHCP server? Please make sure that  the DHCP pool is enough for the client devices.

By the way, do you try to change the ethernet cable? There may be something worng with the cable. 

@cbq 

Yeah. I have updated the firmware + the controller. I also saw at Mesh was enabled, and read that if Mesh is enabled the controller should keep running? 

The APs are running IPs xxx.xxx.1.5 and 1.6. Then we have a USG with its DHCP server running xxx.xxx.1.10 - 1.254. and thats plenty since its a small company. 

So yeah, now just to see if it keeps working :-) thanks again

@Guy-26 maybe take your DHCP upper limit down to .250. I think when the EAP reset they try to connect on .254 before changing to either the reserved ip or the static. Maybe there is some conflict.