1x NIC + 1x TP‑Link TL‑SG105E > No DHCP IP on WAN

[z0rk]

Hi,

Another router on a stick setup question.

I am using Xfinity as my ISP.
I am using OPNsense 26.7

TL-SG108E configuration.

1️⃣ VLAN 10 (WAN/Modem Port)
VLAN ID: 10
Ports:Port 1 → Untagged
Port 5 → Tagged
Ports 2–4 → Not Member

2️⃣ VLAN 20 (LAN‑A, 192.x)
VLAN ID: 20
Ports:Port 2 → Untagged
Port 5 → Tagged
Ports 1, 3, 4 → Not Member

3️⃣ VLAN 30 (LAN‑B, 172.x)
VLAN ID: 30
Ports:Port 3 → Untagged
Port 5 → Tagged
Ports 1, 2, 4 → Not Member

4️⃣ VLAN 40 (LAN‑C, 10.x)
VLAN ID: 40
Ports:Port 4 → Untagged
Port 5 → Tagged
Ports 1–3 → Not Member

5️⃣ PVIDs (Port VLAN IDs)
(see attached)

The modem connects to port 1.
Port 5 connects to PC.

I can ping all subnets. I can access the GUI and SSH. WAN doesn't get an IP address assigned.
WAN is set up to use DHCP for both v4 and v6. All other settings are default.
Initially I left the MAC address blank.
Then I tried setting it to use the MAC address of the physical link, the address of the switch, and a randomly created MAC. I tried these with and without promiscuous mode enabled.
Rebooted the modem/OPNsense in between each setting change as well just for good measure.

No luck at all.

Maybe some wizard can shed some light on this.

Thanks!