GOAL

I want to use the M8550 in Ethernet (EWAN) mode as the router for a Starlink
connection (no Starlink router in the chain).
 

TOPOLOGY

Starlink Standard Dish (HW rev3_proto2) 
  -> Yaosheng 120W Step-Up All-in-One PoE injector (12V input) 
  -> single RJ45 data output 
  -> M8550 WAN/LAN port
 

WHAT WORKS (verified)

- The dish is fully healthy and ONLINE: the local debug page at 192.168.100.1
  shows "Normal Ethernet speeds", "Not obstructed", disablementCode OKAY,
  and "Your browser is online".
- A laptop connected DIRECTLY to the Yaosheng RJ45 data port gets a working
  internet connection (Starlink CGNAT 100.64.x.x) and can reach the internet.
  => So the dish, the PoE injector, the cable and the pinout are all fine.
 

THE PROBLEM

- With the M8550 connected instead of the laptop, the WAN never comes up.
- Status page: Internet Access = Ethernet, WAN interface "ipoe_0_0_d",
  Connection Type = Dynamic IP, but:
    IP Address: 0.0.0.0
    Subnet Mask: 0.0.0.0
    Default Gateway: 0.0.0.0
    Up Time: 0 days 00:00:00
- System Tools > Diagnostics returns:
    "Please check if the LAN or WAN port is properly connected" -> FAIL
- LAN is 192.168.10.1 (no conflict with the dish 192.168.100.1).
 

WHAT I ALREADY TRIED

- Confirmed Ethernet mode is selected and the WAN/LAN port is enabled.
- WAN connection type is Dynamic IP; NAT enabled; MTU 1500.
- Manually clicking "Connect" on the ipoe_0_0_d connection -> stays Disconnected.
- Rebooting the dish AFTER the M8550 is connected (to free the single DHCP lease).
- Power-cycling both devices in different orders.
- Disabling IPv6, IPv4-only.
- Different / short Ethernet cable.
 

WHAT I CANNOT DO

- I wanted to try a manual Static IP (using the values the laptop received from
  Starlink), but on the Network > Internet page the "Internet Connection Type" and
  "Default Gateway" dropdowns are GREYED OUT / disabled on the existing connection.
 

QUESTIONS

1. Is there a known incompatibility between the M8550 EWAN/DHCP client and Starlink's
   DHCP behaviour (short-lived 192.168.100.1 lease, then real IP / DHCP option 121)?
2. How can I switch the existing Ethernet connection to Static IP? The dropdowns are
   disabled - do I have to delete the connection and create a new one, and if so, how?
3. Any recommended workaround?
 

Thank you!