WAN connection getting an IP but no echo request, then drops connection

[Leaferra]

Hi all, very new to the whole "posting in a forum for help" thing so apologies in advance.

I'm attempting to replace my NETGEAR Nighthawk WiFi router with an OPNSense VM on an ESXi host. The router would then be placed into AP mode and only handle WiFi connections.

So far it's all been working on the LAN side, and clients can get IPs, communicate with each other, and access internal resources without issue. The issue comes from the WAN connection that refuses to connect to my ISP for more than a minute at a time.

The WAN interface itself uses PPPoE to connect to my ISP-Provided router, and while the connection is successful and I receive both an IPv4 and v6 address, no packets seem to actually make it out of the network and to my ISP.
From checking the logs, it seems that the connection is made and works as normal up until the IPs are assigned, after which the logs state "lcp no reply to 1 echo request(s) " from 1 to 5 before the connection is dropped. I'm unsure what could be causing this, and any help would be greatly appreciated. I'm happy to show any configs once I'm home later.

N.B: The PPPoE connection works on the NETGEAR router, and I've copied the settings from the router to OPNSense. The connection is also currently active with no issues, so it's definitely something I've misconfigured in OPNSense.