Unexpected behavior on IP Passthrough with Starlink & cg-nat

Hi guys

I’m experimenting with Pepwave’s Starlink integration on a max br1 pro running 8.5.0 rc3 build 5636; Hardware revision 7.

I have a Starlink unit in cg-nat mode (no public IP yet) connected to the br1 Wan port. The Starlink router is in bypass mode, so the br1 gets the cg-nat 100. ip address.

I then enabled IP passthrough on the br1 Wan part to the untagged Lan. The laptop gets the 100. cg-nat IP, and has internet access, as expected.

BUT I would expect the Pepwave itself to no longer have internet access or an IP address on it’s Wan interface, but it does. It has shows the same 100. IP address that my laptop now has.

  • The br1 is checking into inControl.
  • The br1 VPN to our Fusionhub is up, and I am able to reach the BR1 Lan IP. - Our Zabbix monitoring is successfully polling the starlink dish via grpc on 9201 via the br1 lan ip.
  • The laptop has internet and is able to browse reddit.
  • The laptop is running a steady ping to 8.8.8.8
  • My other computer is running a steady ping to the br1 lan IP which is only reachable over the vpn.

How can both devices have the same IP address and internet access?
I can understand maybe Starlink’s cg-nat implementation is ignoring mac-addresses, but the br1 Wan port is in bypass mode, so how does it have an IP address? In my mind, this shouldn’t be working.

While the long term goal is to add an additional connection (a sim card probably) to give the br1 internet for remote management, we have not done that yet.

We will also be using this with a Starlink public IP when the time comes, so I’m wondering if the behavior will be the same.

More unexpected behavior.

Wan: Starlink -=> ip passthrough to vlan 995 on lan 2 trunk
Cell: sim card -=> ip passthrough to vlan 996 on lan 2 trunk
lan 2 -=> switch port 1 in trunk mode

switch port 2: access vlan 995 -=> third party router 1
switch port 3: access vlan 996 -=> third party router 2

Both third party routers are setup with a normal dhcp client and get the IP addesses expected but…

traceroutes on the third party routers to random websites take different paths as seen here:

10.10.10.1 is the lan Ip of the Pepwave.

( small advice, always hide your SN numbers from your peplink devices, you never know… It is in your ic rma URL)

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