The WiFi Settings widget on the router's web interface now has a new Advanced tab where you can configure Client Steering and Node Steering. Both features are enabled by default as recommended and should only be turned OFF as the last resort once you have exhausted all other WiFi troubleshooting techniques.

For a client to roam seamlessly, the client must support 802.11k and 802.11v. For clients that lack 802.11k, a node will not be able to determine where to steer a client or even if a client needs steering. The clients lacking 802.11v, on the other hand, can’t be directed to change to another node.
 
If you know that your device supports 802.11k/v and you have exhausted all other standard WiFi troubleshooting techniques, you can then try to isolate the issue by turning OFF the Client Steering or Node Steering feature as the last resort.
 
For example, if some clients are connected to the 2.4 GHz instead of the 5 GHz, try turning the device OFF/ON first. If the issue continues, isolate it by turning OFF Client Steering to check if this fixes the issue.
 
If a device is connected to the farthest node, try power cycling that node. If the issue continues, then try turning OFF Node Steering to isolate the issue.
 
Disabling the Node Steering option will not affect a mesh network. This will only stop the primary node from sending suggesting connection changes to the secondary nodes.