refresh_dns.py

#! /usr/bin/env python3

import sys

# if the dns server of the wireguard are showed in the resolve.conf, then we skim off other servers to make sure the wireguard has the highest priority.
with open("/etc/resolv.conf") as f:
    old_resolv = f.read()
if "10.56.100.1" in old_resolv:
    with open("/etc/resolv.conf", "w") as f:
        f.write("# generated by /etc/NetworkManager/dispatcher.d/refresh_dns.py\nnameserver 10.56.100.1\n")

refresh_dns.sh

#! /bin/bash

python3 /etc/NetworkManager/dispatcher.d/refresh_dns.py