@TP_AW 

Very interesting.... I sent all my logs to TPLink via the ticket listed in the thread. 

I HAD a OC200 and the same setup for YEARS with ZERO issues.

My issues all started when I added the TP-LINK ROUTER ER707-M2

In trying to trouble shoot I upgraded the OC200 to a OC300, Omada POE Recovery Switches.... and yet the only fix was to role back 1 version to my EAP225's

But something with adding TP-LINK Router triggered it. (I too have multiple SSID's) 

You are not alone!

I was running a Setup with no problem for years.

ER605 v1 (then v2)

1 SG2428P Switch

1 EAP615 Wall (10m lan cable poe connection)

1 EAP225 AP (5m lan cable poe connection)

1 EAP225 Outdoor AP (10m lan cable poe connection)

1 EAP225 Outdoor AP (55m lan cable poe connection)

Then i decided to change the ER 605 with also an ER707-M2 v1.20 for performance reasons.

Since then i had a similar trouble adventure like you.

The EAP 225 Outdoor with the longest cable kept starting disconnecting all the time, i thought maybe a defect, changed it with the one with the short cable for trouble shooting reasons, but the issue still remained. then when i almost wanted to change the cable (after all cable tests said it was good) the non outdoor EAP225 was disconnecting, so i was sure it could not be the cable.

Few things i noticed:

• although the eap was disconnected and showed in the controller it is disconnected, the clients showed up in the controller as "wired" clients and worked but not every time the EAP disconnected
• Overall WLAN Performance decreased except for the 615Wall EAP
• All the trouble started with the ER707-M2 implementing - beevor everything worked at the same setup

Edit 1:

Since downgrad of the EAP225 and Outdoor from 5.1.6 to 5.1.1 everything is back to normal! Even the WebGui ist quciker then bevor.

(to my initial post / response to DACZ post) The downgrade as performed by DACV triggered me ( ;-) something like "what if...").

Over the weekend I downgraded my EAP225 (per version as described by DACV). Just to re-itterate, my EAP225 didn't got in a 'disconnected' state but the EAP245 which it connects to (via mesh) does.

I will let this run over a couple of days and give the results.

(My thoughts at the moment.. is that version 5.1.6 for EAP225 even capable of 'passing' on its irrectic behaviour - or more specificaclly, to its 'nearest' (wired) ethernet connection.... but I am getting a bit ahead of myself... I will post an update later this week)