@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)

Edit (Oct 21):

So I downgraded the EAP225 to v.5.1.1. mesh connected to EAP245-Boven but that didn't help. The EAP245-Boven continued to get in a 'disconnected state' on roughly daily basis. I moved the EAP225 (SSID's #1 & #2)  mesh from EAP-245-Boven (SSID's #2 and #3) to EAP245-Beneden (only having SSID #1) by changing the preferred mesh AP but the EAP245-Boven continues to get in a 'disconnected' state on a daily basis. ( I would have expected the EAP-Beneden would now be the one getting a 'disconnected' state but doesn't).

So in all it is 'wierd'.. I didn't had any problems, I added the ER706, changed the network (logical) layout and 'boom' the EAP-Beneden (having all 3 SSID's at that time) disconnected on a daily basis. I removed 2 of SSID's of that EAP and teh problems disappeared for that EAP. Yet, the problems started on teh EAP-Boven (which had the mesh with the EAP225). But regardless (including the actions above) didn't result in the EAP245-Boven not having the 'disconnected' state anymore (continues to get in a 'disconnected' state). 

Next action: re-enstate all SSID's on EAP-Beneden again and see what happens.

Picture of the current connectivity model, for versions, see my first post.

  @DACZ 

Anything new on this topic?

  @npalko 

I upgraded my ER707-M2 to v1.2.3 and thought.... Wonder if that fixes the 5.1.6 firmware issue on the EAP 225. So I upgraded 4 of them. Nope, this morning they were all DISCONNECTED. I rolled back to 5.1.1. Thankfully I have POE Recovery switches, so I can do this from my desktop. Otherwise you have to cut power to the device, let it re-establish the connection and then roll back the firmware, some of my device locations, this wouldn't be fun (like my Garage Ceiling) where one of the EAP225 devices is. 

My EAP620 is wanting to upgrade from 1.2.6 to 1.3.1 but I am reluctant... 

I e-mailed SUPPORT again today, I suggested they either FIX 5.1.6 or simple REMOVE it and keep 5.1.1 as the current version. 

I think the ER707 has issues.... but that is another topic. I'm running 2.5Gig IN / OUT of that device (multiple VPN's etc). 

  @npalko 

I just got this email from TP-Link Support

In addition to my previous replies/info,

As mentioned, I still had an issue with one of my EAP245's (wired connection to my SG2210MP (Main Switch) which initially had the EAP225 (wireless meshed connection) connected to it. Shifting it over the other EAP245 didn't help. 

But what helped, apparently I had selected on the 5Ghz band SSIDS a bandwidth of 80Mhz. Ever since I changed that back to 'automatic' the EAP245 doesn't get in a disconnected state anymore (so I now have a 'stable' environment again) -and the kids are no longer complaining about bad WIFI :-)  - 

  @DACZ Thansk for the information, then we have to wait and see, soon hopefully *g*