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...

[z0rk]

Thank you for your questions.

I am using an ARRIS (SB6190-RB) Cable Modem it comes preconfigured in bridge mode. There's no additional setup required. I plug it into the WAN port of my current OPNsense box and voila.

The TP-Link TL-SG108E is v5 and has the most current firmware installed. All settings are left at default with the exception of the 802.1Q VLAN Configuration and the 802.1Q VLAN PVID Setting. I've attached those settings and hopefully that will clear things up.

Thank you

[nero355]

I am using an ARRIS (SB6190-RB) Cable Modem it comes preconfigured in bridge mode.
There's no additional setup required. I plug it into the WAN port of my current OPNsense box and voila.

At least that's clear now! :)

The TP-Link TL-SG108E is v5 and has the most current firmware installed.

Sounds new enough...

And if it's not the 5-port version then please edit the title of the topic to avoid confusion! ;)

All settings are left at default with the exception of the 802.1Q VLAN Configuration and the 802.1Q VLAN PVID Setting.
I've attached those settings and hopefully that will clear things up.

One more thing :

Am I right when I say you are using VLAN 1 to transport the Cable Modem to the OPNsense Router connection ?
IIRC that's a bad idea because it might expose the webGUI of your Switch to the Internet !!

Therefor I suggest using a new VLAN for the same purpose : Let's say 50 and make sure it's UNTAGGED at Port 1 and TAGGED at Port 5.
After that you need to adjust your OPNsense configuration too for your WAN and use VLAN Interface 50 as the WAN Connection instead of the NIC Interface itself :)
/EDIT :
Never mind... I misread the whole thing completely... d0h!

This seems to be the case indeed :

According to the screenshot you are getting WAN on VLAN10 on port 1 and port 5 is your trunk port.

Thnx! for noticing! :)


Also :
What does your OPNsense configuration look like ?

[patient0]

All settings are left at default with the exception of the 802.1Q VLAN Configuration and the 802.1Q VLAN PVID Setting.

According to the screenshot you are getting WAN on VLAN10 on port 1 and port 5 is your trunk port. _But_ ythe ports 1-5 are set as untagged for VLAN1 and you also set port 1-4 as untagged for VLAN10/20/30/40.

That will not work, one port can only ever have one PVID set (that looks correct in the other image) which results in that each port can only ever be set as untagged for one VLAN.

In '8012.1Q Configuration': VLAN10 - 40 are set correct but for VLAN1 you have to set untagged for port 5 (becaue port 5 has PVID 1) and I wouldn't set any port to tagged for VLAN1. Because you don't want VLAN1 on any of the other ports. You have port 1-4 configured as Access Ports (Cisco lingo, 'Native VLAN' in UniFi lingo) and there is no reason to carry VLAN1 as tagged traffic on these ports.

With that you can receive WAN traffic on VLAN10 in OPNsense. So I assume you configured your WAN as a VLAN10 interface in OPNsense?