No connection with wireguard


I've set up wireguard on my WRT3200ACM and my Android phone but I don't get a connection. According to the log on the wireguard app it's stuck on key exchange. It's seems as if it does not get a connection. On the OpenWrt there is no indication that a connection attemp occurred.

This is what I have on the OpenWrt:

In /etc/config/network

config interface 'wg'
option proto 'wireguard'
list addresses ''
option listen_port '1080'

config wireguard_wg
list allowed_ips ''
option persistent_keepalive '25'

In /etc/config/firewall:

config rule
option target 'ACCEPT'
option src 'wan'
option name 'WG Road Warrier'
option proto 'udp'
option dest_port '1080'

config zone
option name 'wg'
option forward 'REJECT'
option output 'ACCEPT'
option network 'wg'
option input 'REJECT'

config forwarding
option dest 'dmz'
option src 'wg'

config forwarding
option dest 'wan'
option src 'wg'

What am I missing? Is there any tool to test if I can get a udp connection from the phone to my server? Maybe the udp packets are filtered somewhere?