No ping after applying WAN settings update

[greyday]

Hi--pretty new to the system so apologies if this is obvious, but I had everything set up and running just fine; I went to start configuring my first LAN and noticed that the WAN default setting did not have the "Prevent Interface Removal" option clicked, so I clicked it. That is the only change I made. I saved and applied changes and immediately lost connection with the firewall. I tried rebooting it and nothing. Pings fail, though it does show up on a LAN scan (may just be a ghost image, LANScan takes a while to "forget" things). I tried connecting to another LAN and same thing--showed up on network, identified by name, no ping and no response to ssh or the panel.

Is there a reason this happened? How can I fix it? I have the install on a headless 1U rig, so I would have to disassemble it and another box to get a gpu connected and connect directly, so thought I'd check here first to see if there's any kind of quicker fix before tearing apart my builds