@Yags 

Hey and Welcome!

Can I ask do you have a controller in play on the network?   Something like the OC200 or a software controller?

My thinking is that if you don't, then you are not going to get any type of WiFi load balancing / roaming as each AP will work as its own entity.   You may find that one AP is busy, other 2 less so and therefore congestion!

Bear in mind that the EAP225s are WiFi5 grade devices so top out performance wise around 450/500mbps in "real speeds". Obviously as you add more clients to the airspace this is subject to more latency and performance drops.   The only way round this is wifi load balancing via roaming / AI roaming and that requires a controller in play.

  @Philbert 

I am not using any Controller. Also i am disable all controller setting on my EAP225 and TL-R605.

  @Yags 

Hey

It may be wise, especially as you have 3x APs to consider adding a controller to your system.  Even should this just be for the APs

The reason I say this is the error you posted   SSID and Channel because WAP authentication time out/failed    is usually caused by weak signal and from experience this is more common in standalone installations like yours.   Basically the client is trying to hold authentication with an AP, but the signal is too poor and therefore it fails.   At that stage the client will search for another known SSID to connect too, likely the same SSID but a different AP.    The only way to start to negate this is via roaming and management, which requires a controller.