I have acl only for comments for registration table.
-120..+120 allow.
For exapmle:
add action=accept comment=RN3Pro disabled=no mac-address=64:CC:2E:B9:38:7B signal-range=-120..120 ssid-regexp=""

With acl phone is trying to roam anyway. Got connection drop(acl) and reconnect again to closest AP with 4way handshake, dhcp... And repeat it again till 30 seconds.
And again and again. After some time it stop connecting at all.

Why client decision to roam depends on firmware of router?
Explain this.

Redmi Note 3/Mi5s plus is not so old or buggy devices...
The router must do his job! I do not have to select compatible devices with it. You can't explain that to boss or client.

What about rates setting? Some android devices will draw back to 802.11b rate when sleeping, it will drop connection if your AP doesn't do 802.11b rate Switched from 5ghz-onlyac and 2ghz-onlyn to 5ghz-a/n/ac and 2ghz-bgn.... Nope. Same thing with roaming. No battery drain. P.S. Rollback to LT 6.44....

Regarding the battery drain, did you set "Multicast Helper" to full? I noticed if I have this enabled, my client will wake up every second as the "Last Activity (s)" shows in "Registration" will always below 1.00, this may indicated that clients are awaken in every sec...

Access list is just a way to improve the Roaming, it is something like a workaround..nothing more nothing less... But... This does not change the Fact that the client makes the decisions... Either if we talk about 802.11r or 802.11k or simple roaming... ACL causes connection drop and re registering...

And to be boring again: a stronger AP signal does not help much. Wifi is bidirectional, if the AP cannot receive the device, there is no communication possible.https://metis.fi/en/2017/10/txpower/ It happends in 1-3 meters from AP. It ALWAYS happend with low rates, when phone is trying to sleep. An...

I noticed today that this happens when the phone tries to enter sleep mode. And it droppin RX/TX rates.... MB there is a way to forbid low rates?
UPD. And look like it helps.

No, it didn’t help. Maybe a little better.

Yes. Rejected as expected. With ACL reject phone looses internet connection every 1-2 minutes. And it somtemes stop trying to connect wifi at all. Don't be so boring about IP address.:) I've just don't want to reveal real addresses.... Mikrotik will never allow you to enter a completely wrong addres...

hAP AC2 main51 cAP AC kit51 AC:C1:EE:44:B2:CB Xiaomi phone No ACL 20:26:36 caps,info AC:C1:EE:44:B2:CB@main51 disconnected, registered to other interface 20:26:46 caps,info AC:C1:EE:44:B2:CB@main51 connected, signal strength -82 20:26:46 caps,info AC:C1:EE:44:B2:CB@kit51 disconnected, registered to ...