SearXNG opensearch.xml works through LAN, but not through NetBird

[MorsMortium]

Describe the problem

I'm using the free tier of NetBird available from the website. I have set up an instance of the SearXNG search engine on one machine, that's added to my machines. I have set up SearXNG IP to be the one shown by NetBird. From another machine I can access the engine, search, save settings, etc., but if I try to add the engine to Firefox, which uses opensearch.xml, it fails to do so.
I have set the IP of SearXNG to the router provided IP, when the 2 machines were in the same LAN, and then adding the engine worked. I have tried both the AUR and the Docker image of SearXNG with the same results.

The error message is the following:

Firefox could not download the search plugin from: http://100.78.162.141:8888/opensearch.xml?method=GET&autocomplete=

To Reproduce

Steps to reproduce the behavior:

1. Add 2 machines to NetBird
2. Install and set up SearXNG on one machine, based on these docs: https://docs.searxng.org/admin/installation-docker.html or on an Arch Linux system through this package: https://aur.archlinux.org/packages/searxng-git
3. Confirm that the engine is usable from the other machine
4. Try to add the engine with right clicking into the address bar, when on the engines page and clicking Add "my-instance"
5. See error

Expected behavior

That Firefox successfully adds the engine to it's engine list, as it does through the exact same setup, using the LAN IP.

Are you using NetBird Cloud?

I use the the version hosted by NetBird on https://app.netbird.io/

NetBird version

0.33.0 on both machines

NetBird status -dA output:

Client:

Peers detail:
 server.netbird.cloud:
  NetBird IP: 100.78.162.141
  Public key: JZP73b/7q82v6fD05jP8ArSc4dXFkv8QUWpgktW0PlU=
  Status: Connected
  -- detail --
  Connection type: P2P
  ICE candidate (Local/Remote): srflx/srflx
  ICE candidate endpoints (Local/Remote): 198.51.100.0:5838/198.51.100.1:51820
  Relay server address: rels://streamline-de-fra1-0.relay.netbird.io:443
  Last connection update: 21 seconds ago
  Last WireGuard handshake: 21 seconds ago
  Transfer status (received/sent) 37.5 KiB/15.0 KiB
  Quantum resistance: false
  Routes: -
  Latency: 38.338984ms

OS: linux/amd64
Daemon version: 0.33.0
CLI version: 0.33.0
Management: Connected to https://api.netbird.io:443
Signal: Connected to https://signal.netbird.io:443
Relays: 
  [stun:stun.netbird.io:5555] is Available
  [turns:turn.netbird.io:443?transport=tcp] is Unavailable, reason: dial: d.Dialer.DialContext: dial tcp 198.51.100.2:443: connect: no route to host
  [rels://streamline-de-fra1-0.relay.netbird.io:443] is Available
Nameservers: 
FQDN: phone.netbird.cloud
NetBird IP: 100.78.36.177/16
Interface type: Kernel
Quantum resistance: false
Routes: -
Peers count: 1/1 Connected

Server:
I'll add it soon, but they are the exact same distros with exact same package and NetBird versions and use the exact same router through a switch

Do you face any (non-mobile) client issues?

Client:
netbird.debug.3764821383.zip

Server:
I'll add it soon, but they are the exact same distros with exact same package and NetBird versions and use the exact same router through a switch