The error i get is:

Error: argument "suppress_prefixlength" is wrong: Failed to parse rule type

Here is the detailed output:

root@freepbx ~# wg-quick up wg0

[#] ip link add wg0 type wireguard

[#] wg setconf wg0 /dev/fd/63

[#] ip address add 10.1.9.4/16 dev wg0

[#] ip link set mtu 1420 dev wg0

[#] ip link set wg0 up

[#] wg set wg0 fwmark 51820

[#] ip -4 route add 0.0.0.0/0 dev wg0 table 51820

[#] ip -4 rule add not fwmark 51820 table 51820

[#] ip -4 rule add table main suppress_prefixlength 0

Error: argument "suppress_prefixlength" is wrong: Failed to parse rule type

[#] ip -4 rule delete table 51820

[#] ip link delete dev wg0