Wireguard Roadwarrior Setup - Need assistance

[snejball]

Cheers,

I am at a loss and need some help troubleshooting my WG Roadwarrior Setup:
One Opnsense Instance configured with two peers: Android Phone and a Fedora 39 Laptop.

Working fine with the android, no problems here. On the Fedora it seems no handshake can be completed.
When running a capture on both laptop and opnsense I see the 148 Byte Handshake leaving the laptop via correct interface and arriving at opnsense WAN Interface. However opnsense just refuses to answer. Kernel Debugging on Fedora shows Handshake timeout after 5 seconds and then tries again and again.
Does anyone have an idea, where to look?

By default both fedora and opnsense use ipv6, but reverting to IPv4 shows no difference

Config on Fedora:
[Interface]
Address = 172.16.255.2/32, <somestaticGUA>/128
DNS = 10.0.200.2, 2a02:8106:54:7a82:8c1a:7a3a:7bf5:d89c
PrivateKey = <veryprivatekey>

[Peer]
AllowedIPs = 0.0.0.0/0, ::/0
Endpoint = gw.snejball.de:51820
PublicKey = L4A07c4tgkBH79g2gHUbhlMXcNV8NKwBaoTAvTxAiDM=