What is a default gateway?
The default gateway is how you able to reach the Internet (or other networks) from your private network. Without a default gateway, you will not be able to download or upload information to the Internet, thus Pi-hole will not work since it cannot send queries to upstream servers.
In many home setups, your default gateway will be your wireless router. As part of our debug process, we check that the gateway is
pingable and that traffic can be routed through it. If you see any failures in your debug log, you should check to make sure your gateway is working properly and your clients are configured to use it.
If your gateway does not respond to
pings, it doesn't necessarily indicate a problem. Your router (gateway) may simply be configured to not respond to
pings, but still allow traffic to pass through it.
Finding your default gateway
You can find your IPv4 and/or IPv6 default gateway with these commands:
ip -4 route | grep default | cut -d ' ' -f 3 ip -6 route | grep default | cut -d ' ' -f 3