I have 3 wg interface on my server, but I am unable to enable wg0 with wg-quick at boot:

@ubuntu:~$ sudo systemctl enable wg-quick@wg0
@ubuntu:~$ 

Oct 06 13:22:51 ubuntu systemd[1]: Starting WireGuard via wg-quick(8) for wg0...
Oct 06 13:22:51 ubuntu wg-quick[1737]: Warning: `/etc/wireguard/wg0.conf' is world accessible
Oct 06 13:22:52 ubuntu wg-quick[1737]: [#] ip link add wg0 type wireguard
Oct 06 13:22:52 ubuntu wg-quick[1737]: [#] wg setconf wg0 /dev/fd/63
Oct 06 13:22:52 ubuntu wg-quick[1737]: [#] ip -4 address add 192.168.5.2/24 dev wg0
Oct 06 13:22:52 ubuntu wg-quick[1737]: [#] ip link set mtu 1420 up dev wg0
Oct 06 13:22:53 ubuntu wg-quick[1737]: [#] ip -4 route add 192.168.2.0/24 dev wg0
Oct 06 13:22:53 ubuntu wg-quick[1737]: [#] iptables -A FORWARD -i wg0 -j ACCEPT; iptables -A FORWARD -o wg0 -j ACCEPT; iptables -t nat -A POSTROUTING -o e
Oct 06 13:22:53 ubuntu wg-quick[1737]: Another app is currently holding the xtables lock. Perhaps you want to use the -w option?
Oct 06 13:22:53 ubuntu wg-quick[1737]: [#] ip link delete dev wg0
Oct 06 13:22:53 ubuntu systemd[1]: wg-quick@wg0.service: Main process exited, code=exited, status=1/FAILURE
Oct 06 13:22:53 ubuntu systemd[1]: Failed to start WireGuard via wg-quick(8) for wg0.
Oct 06 13:22:53 ubuntu systemd[1]: wg-quick@wg0.service: Unit entered failed state.
Oct 06 13:22:53 ubuntu systemd[1]: wg-quick@wg0.service: Failed with result 'exit-code'.

As you can see it fails at iptables command.

wg0, wg2 fails with this problem, but wg1 starts without problem (same config, with iptables command).