XG-7100 WAN on ix0 tagged VLAN

[Setarcos]

Hi folks,

New XG-7100 owner here so please excuse my ignorance on this.

I currently have the WAN interface using the default VLAN 4090 on lagg0 connected to a cable modem (dual stack using DHCP/DHCP6) and ix0 trunked to a Unifi pro-series switch with four VLANs defined. This setup seems to work fine, and I have no issues with device, VLAN or WAN connectivity. However, I attempted to reassign the WAN interface to another VLAN on ix0, but it doesn't seem to be behaving correctly. I did a factory reset on the cable modem to reset any client MAC affinity each time I moved the modem, but on the XG-7100 I can't see any MACs arping on that VLAN, nor am I able to get a lease via DHCP/DHCP6 for the WAN interface. On the Unifi switch VLAN I see the cable modem MAC and the MAC for the XG-7100's ix0 native (untagged) VLAN which seems a bit odd as this should show the tagged VLAN interface. Prior to reassigning the WAN interface to this VLAN I see ix0's native VLAN ARPing on the correct native VLAN on the switch. I ended up having to move the WAN interface assignment back to VLAN 4090 on lagg0 and the cable modem back to the XG-7100 switchport assigned to VLAN 4090 to get things working again.

Any idea what could be happening, or what i should look at next?

TIA!

[Setarcos]

Just an update on this for anyone interested.

This ended up being an issue on the Unifi switch side due to what appears to be a bug in the 4.3.13.11253 USW-Pro firmware. For some reason it was blocking tagged traffic from ix0.100 on the trunk port from reaching the untagged switch ports assigned to VLAN 100.