Traffic forwarding works on TCP but fails on UDP

I wanted to expose an IPcam to Internet using WireGuard tunnel, diagram looks like this:

Client --—> ServerA -—-(wireguard)---> ServerB ---(LAN)--—> Cam 

I've set proper DNAT and SNAT rules; but only TCP works, UDP doesn't. 🤔

ServerA rules:

table inet filter { chain prerouting { type nat hook prerouting priority 0; policy accept; ##IPcam - forwards to ServerB iifname eth0 tcp dport 5541 dnat ip to 192.168.2.2:5541 iifname eth0 udp dport 5541 dnat ip to 192.168.2.2:5541 } chain postrouting { type nat hook postrouting priority 0; policy accept; oifname eth0 masquerade ##IPcam oifname wg2 ip daddr 192.168.2.2 tcp dport 5541 snat to 192.168.2.1 oifname wg2 ip daddr 192.168.2.2 udp dport 5541 snat to 192.168.2.1 } } 

ServerB rules:

table inet filter { chain prerouting { type nat hook prerouting priority 0; policy accept; ##IPcam - Forwards to actual cam iifname wg0 tcp dport 5541 dnat ip to 192.168.5.63:554 iifname wg0 udp dport 5541 dnat ip to 192.168.5.63:554 } chain postrouting { type nat hook postrouting priority 0; policy accept; oifname eth0 masquerade } } 

When streaming using TCP it works perfectly, but UDP does not work.

// tcp works mpv --rtsp-transport=tcp rtsp://serverA:5541/Streaming/Channels/1 // udp not work mpv --rtsp-transport=udp rtsp://serverA:5541/Streaming/Channels/1 

Even though rules for UDP and TCP are same, why TCP work but UDP fails?

ChatGPT spitting out garbage, any help would be highly appreciated. 🙏