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!

---
Edit:
I've tried using the MAC address of my current OPNsense box, set VLAN priority to 6 and 7 respectively, but I am still having the same issue.

tcpdump -ni re0_vlan10 port 67 or port 68
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on re0_vlan10, link-type EN10MB (Ethernet), snapshot length 262144 bytes
16:29:15.088863 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:29:26.118714 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:29:48.321257 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:29:50.349083 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:29:55.381867 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:30:09.383068 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:30:29.402982 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:30:36.421088 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:30:48.423105 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:31:04.452439 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:31:05.516106 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:31:07.580611 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:31:12.586850 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:31:22.670109 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:31:33.703175 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:31:48.722855 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:32:11.326441 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:32:16.327227 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
16:32:25.352865 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:b7:85:1f:be:ad, length 300
^C
19 packets captured
141 packets received by filter
0 packets dropped by kernel

[nero355]

I am using Xfinity as my ISP.

Do you know THE CORRECT settings for that ISP ?!

Are you using a Bridged Cable Modem or Glassfiber ONT ?
Or NAT behind NAT perhaps ?

TL-SG108E configuration.

Title says TL-SG105E ?!

I am confused by this :

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)

What makes the attached screenshot different compared to all that data ?!

Reason I am asking :
Your attached screenshot suggests Port 5 only has VLAN 1 TAGGED ?!

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

Client PC or OPNsense Router 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.

Please post your network setup and how you have connected everything.

Initially I left the MAC address blank.

As you should unless you need to Clone the MAC Address of the Router provided by your ISP.

Rebooted the modem/OPNsense in between each setting change as well just for good measure.

And the Switch ?

There are known old Revision+Firmware combinations that had issues applying the configuration correctly so if yours is very old that might be a possible issue...