its not roaming
You put some kind of meaning in the concept of wifi roaming.
From the station's point of view, it is roaming.
If the station is roaming disabled, then the station will be connected to one access point and will not look for another access point until the connection is broken, only then the station will try to start a new connection. Scans the air and connects to an AP with a given SSID.
If the station is roaming, the station will search for another AP in the background when the signal level from the connected AP drops to -68-70, if it finds another AP with a better signal then the station will disconnect from the old AP and start the procedure of connecting to the new AP.
Inclusion of roaming mode on the station increases the signal delay, since part of the airtime is spent on scanning the air, and the weaker the signal from the swap, the delay is greater, as the data transmission rate is lower. No other advantages are given by the inclusion of roaming mode at the station.
https://wiki.mikrotik.com/wiki/Manual:I ... on-Roaming
The time it takes for the station to connect to a new access point varies depending on the data transmission speed and workload of the access point and can take up to 30 seconds, and in some cases may be up to 2 minutes. No change in station settings can reduce this time. It can only be reduced by changing the access point settings.
Significantly reduces the time of transition of the station to a new access point (up to the loss of 0-10 packets) is the transfer of the network of access points under the control of Capsman.
PS There are extensions to the 802.11 standard for roaming, but Hap ac2 does not support them.