cmatte

Same results for both, ipv6 dependency, ipv6 is loaded indeed, are you getting anything different from a:

modprobe wireguard

or the 

ip link add dev wg0 type wireguard

?

Good to try. Many other answers point towards installing your kernel headers, so tried but the link seems dead on the OpenPLI feed.

modprobe wireguard
modprobe: ERROR: could not insert 'wireguard': Unknown symbol in module, or unknown parameter (see dmesg)

dmesg

[ 5432.403153] wireguard: Unknown symbol udp_sock_create4 (err 0)
[ 5432.409019] wireguard: Unknown symbol udp_tunnel6_xmit_skb (err 0)
[ 5432.415348] wireguard: Unknown symbol udp_tunnel_sock_release (err 0)
[ 5432.421812] wireguard: Unknown symbol setup_udp_tunnel_sock (err 0)
[ 5432.428090] wireguard: Unknown symbol udp_sock_create6 (err 0)
[ 5432.433976] wireguard: Unknown symbol udp_tunnel_xmit_skb (err 0)

Attempting WG install on vuduo4k on 7.3, gets stuck at the instructions:

ip link add dev wg0 type wireguard
ip: RTNETLINK answers: Operation not supported

wget: server returned error: HTTP/1.1 404 Not Found
Collected errors: * opkg_download_backend: Failed to download http://downloads.openpli.org/feeds/openpli-7-release/armv7ahf-neon/linux-libc-headers-dev_4.10-r0.2_armv7ahf-neon.ipk, wget returned 1. * opkg_install_pkg: Failed to download linux-libc-headers-dev. Perhaps you need to run 'opkg update'?
Installing linux-libc-headers-dev (4.10) on root
Downloading http://downloads.openpli.org/feeds/openpli-7-release/armv7ahf-neon/linux-libc-headers-dev_4.10-r0.2_armv7ahf-neon.ipk.