VPN Server issue Flint & Opal

Hi Guys,

I am new to this, but I am trying to setup a home VPN Server using Flint AX1800 and an Opal as VPN client. The Flint sits behind my ISP Fritzbox from Vodafone. The setup is like this, My ISP Fritzbox gives out IP in range of 192.168.178.0/24, so I connect to one of the LAN port of the Fritzbox to the WAN port of the Flint and configure a static IP for it as 192.168.178.10. The Flint has a local LAN of 192.168.8.0/24 which I did not change. On the Fritzbox I did a port forward to UDP port 51820 because I only want to setup WireGuard for now. But when I configure my Opal using the client config it is not connecting. I did the same with my phone using the wireguard app, and the always initiating handshake.

I already enabled DDNS on the Flint. During some small troubleshooting I notice the flint is able to pick up the an public IPv4 address from my ISP. I don't know exactly what I am doing wrong

root@GL-AX1800:~# nmap -sU -p 51820
Starting Nmap 7.80 ( https://nmap.org ) at 2024-07-16 13:37 CEST
Nmap scan report for ip-.um10.pools.vodafone-ip.de ()
Host is up (0.012s latency).

PORT STATE SERVICE
51820/udp open|filtered unknown

Nmap done: 1 IP address (1 host up) scanned in 0.79 seconds

root@GL-AX1800:~# wg show
interface: wgserver
public key: [redacted]=
private key: (hidden)
listening port: 51820
fwmark: 0x8000

peer: [redacted]=
preshared key: (hidden)
allowed ips: 10.0.10.2/32
persistent keepalive: every 25 seconds

root@GL-AX1800:~# netstat -tuplna | grep 51820
udp 0 0 0.0.0.0:51820 0.0.0.0:* -
udp 0 0 :::51820 :::* -

Can someone help

Hi,

please read How to troubleshoot WireGuard as it might guide you through all things you need to check.

Make sure you have a real public IP and you are not behind CGNAT. If you are using Vodafone Cable Internet, you will have CGNAT for sure.