Client roaming between AP's issues

Hello,

In the last 3-4 months we have faced some very unwanted behavior when roaming devices between access points that we have in our environment.

Our scenario and what we've already tried:

-Both sophos firmware and access point firmwares are up to date
-6x APX530 and 4x APX320 spread across three floors. (Floor 1 - 4x APX320, Floor 2 - 3x APX 530, Floor 3 - 3x APX530)
-Fast transition activated on WLAN's, WPA2 Personal/AES encryption.

-We tried different signal strengths, and channel width.
-Use only the 5GHZ network.
-Use only the 2.4GHZ network.
-Update client device's drivers
-Dyn-chan configuration

One issue they usually claim is the device driver that may be causing this, but in environments with AP's from other vendors the problem does not occur. And if it was the driver, as they claim, when we have a bad signal quality, roaming should be triggered once the device should identify that it is necessary. However, this does not happen, the device literally runs out of internet connection while holding a terrible signal at a distant access point that was initially connected, and only disconnects from that access point after disabling and enabling Wi-Fi, only after that workaround, the device disconnects from the AP it was on and connects to the closest one.

However, this process of having to keep reconnecting the wi-fi to normalize the connection is causing extreme discomfort, since we purchase devices for the corporate size, expecting extreme robustness. And we are faced with an environment more unstable than many homes with routers and low-quality residential AP's.

Thanks for the help.