RB4011iGS+ with v7.8: Unifi US-8-60W switch lose connection

RouterOS General
1

After upgrading to v7.8, a switch loses connectivity (Unifi US-8-60W). The switch is connected directly to the RB4011iGS+ and has been working fine for a long time.
The lights in the switch are blinking normally, and the Ethernet interface in the router looks OK, but the switch and the devices behind it lose connectivity after a while. After rebooting the switch or rebooting the interface from the router, the connection is restored, but after a while it fails again.

Does anyone know what might be happening? I’ve tested a replacement switch (same model) and the problem doesn’t go away.

The problem started immediately after upgrading from v7.7 to v7.8. I downgraded back to v7.7 expecting everything to go back to normal…

Thanks for the help !

2

After rolling the router back to v7.7, the switch works as expected.
In v7.8, I disabled the Spanning Tree protocols on the switch and router (I don’t know why, but I tried), but the switch continues to lose connectivity.

What other protocols or mechanisms could be causing the problem with the switch?

The switch works as expected up to v7.7, but in v7.8 it permanently loses connectivity after an unspecified amount of time (from a few seconds/minutes to a few hours).

Thank you very much for any advice.