Unifi switches have been witnessed blocking traffic to a port attached to a Huawei (eg. Spark supplied) router. A symptom is often that attached devices can't get DHCP addresses and the switch itself defaults to the 192.168.1.20 address.
When the switch is adopted in a local controller it can be seen to have "Blocked" status for the specific port.
This seems to be caused by invalid RSTP (Rapid Spanning Tree Protocol) packets coming from the Huawei. The Unifi switch sees it as if it is attached to itself upstream and so blocks the port.
Workaround: Disable RTSP for the specific port that the router uplink is attached to.