bypass mtu limitation

udp2raw by default support MTU max at around 13xx, depending on what kind of VPN you are using. (although I am usually suggesting 1200)

In case you need MTU >13xx, it's a well-known problem which can be near perfectly sloved by chaining UDPspeeder in between:

wireguard_client-->udpspeeder_client-->udp2raw_client---------(internet)---------->udp2raw_server-->udpspeeder_server-->wireguard_server

UDPspeeder (with --mode 0, the default mode) supports both user space package splitting and FEC, it allows you to send large packet efficiently without enlarge the network packet loss (maybe this is the only efficient way ever). But you might need to tune parameters.