Roaming Assistant causes connectivity problems

[Firepig]

Roaming Assistant seems to have been the source of the connectivity problems that have been plaguing me for years. I have had persistent problems with phones (OnePlus phones) and printers not able to get a valid IP address. Phones would show "Connected No Internet". Rebooting the device would cure the problem for a while, then it would recur after a few hours. Devices, particularly printers (turned on and off regularly) seemed reluctant to connect to the nearest access point. Sometimes it was necessary to reboot the main router to get a device online. The issue could even crash the wireless functions of the phones, requiring a phone restart.
I have a DSL-AC88U as the main router and DHCP server, with an RT-AC87U and an RT-AC1200G both connected by ethernet acting as wireless access points, in AP mode. All using the same SSID, for both 2.4 and 5GHz bands.
Trawling through the settings, I noticed inconsistent settings on the three access points for whether Roaming Assistant was enabled. I enabled it on all three at the default values, and instantly the problems got far worse, with the phone not staying connected for any length of time at all.
So I disabled Roaming Assistant on all three access points, and immediately the issues went away. The phone is able to retain connection throughout the house and has not needed a reboot. The printer is stable and connected to the main router next to it.
So I'm posting a solution, rather than a problem. Though I would love to understand it better.
Firepig

 

[OzarkEdge]

Roaming Assistant seems to have been the source of the connectivity problems that have been plaguing me for years. I have had persistent problems with phones (OnePlus phones) and printers not able to get a valid IP address. Phones would show "Connected No Internet". Rebooting the device would cure the problem for a while, then it would recur after a few hours. Devices, particularly printers (turned on and off regularly) seemed reluctant to connect to the nearest access point. Sometimes it was necessary to reboot the main router to get a device online. The issue could even crash the wireless functions of the phones, requiring a phone restart.
I have a DSL-AC88U as the main router and DHCP server, with an RT-AC87U and an RT-AC1200G both connected by ethernet acting as wireless access points, in AP mode. All using the same SSID, for both 2.4 and 5GHz bands.
Trawling through the settings, I noticed inconsistent settings on the three access points for whether Roaming Assistant was enabled. I enabled it on all three at the default values, and instantly the problems got far worse, with the phone not staying connected for any length of time at all.
So I disabled Roaming Assistant on all three access points, and immediately the issues went away. The phone is able to retain connection throughout the house and has not needed a reboot. The printer is stable and connected to the main router next to it.
So I'm posting a solution, rather than a problem. Though I would love to understand it better.
Firepig

How far apart are your APs? Did you ever try raising the Roaming Assistant band RSSI threshold(s) (less negative, roam sooner)?

OE

 

[Ronald Schwerer]

If the threshold is unrealistic for your environment and a compromise threshold can't be found, it is best to disable Roaming.
Check the Wireless log to see what the current clients RSSI values are. If any are below (more negative) that the setting in Professional, try lowering the threshold.

 

[thiggins]

You have learned the hard way that devices control when and where to roam. APs can use various techniques to "encourage" devices to move, which usually include forcing disconnections. But a device's roaming logic can just interpret that as a connection problem and keep trying to reconnect. If neither AP nor STA gives up trying to force the other, then you get what you got.

 

[Firepig]

How far apart are your APs? Did you ever try raising the Roaming Assistant band RSSI threshold(s) (less negative, roam sooner)?

OE

The APs are about 50ft away from the router and each other, through several walls. I haven't tried adjusting the threshold, but it sounds as if the problem is disconnecting too often, rather than not often enough.

 

[Firepig]

You have learned the hard way that devices control when and where to roam. APs can use various techniques to "encourage" devices to move, which usually include forcing disconnections. But a device's roaming logic can just interpret that as a connection problem and keep trying to reconnect. If neither AP nor STA gives up trying to force the other, then you get what you got.

That sounds a very plausible explanation, thanks. I think I'm content just to leave Roaming Assistant off - presumably it means the phones may not always be on the fastest connection, but at least they are connected.

 

[Firepig]

If the threshold is unrealistic for your environment and a compromise threshold can't be found, it is best to disable Roaming.
Check the Wireless log to see what the current clients RSSI values are. If any are below (more negative) that the setting in Professional, try lowering the threshold.

The lowest I can see on any of the three devices at present is -76DB, but presumably that changes as phones roam around the house.

 

[OzarkEdge]

The APs are about 50ft away from the router and each other, through several walls. I haven't tried adjusting the threshold, but it sounds as if the problem is disconnecting too often, rather than not often enough.

50 feet is not too close and not very far, so clients could see multiple/competing strong signals and the routers may not object to using their signal... if the RSSI thresholds are not in play.

By raising (less negative) the RSSI threshold, particularly for the 2.4 band that travels far, you put them into play.

Easy to test, anyway.

OE