networking.wireguard.interfaces.<name>.peers.*.endpoint

Endpoint IP or hostname of the peer, followed by a colon, and then a port number of the peer.

Warning for endpoints with changing IPs: The WireGuard kernel side cannot perform DNS resolution. Thus DNS resolution is done once by the wg userspace utility, when setting up WireGuard. Consequently, if the IP address behind the name changes, WireGuard will not notice. This is especially common for dynamic-DNS setups, but also applies to any other DNS-based setup. If you do not use IP endpoints, you likely want to set networking.wireguard.dynamicEndpointRefreshSeconds to refresh the IPs periodically.