When I add a network range as AllowedIPs, e.g. wg set wgvpn peer abcd… allowed-ips ::/0, then that network is removed from all other peers.
How do I add the same AllowedIPs to multiple peers?
The reason I want to do this is to create a full mesh, and play around routing around down peers.
Do I need to set up separate wireguard interfaces for this?
How do I add the same AllowedIPs to multiple peers?
You don't.
AllowedIPs isn't only a list of allowed IP addresses – the interface also uses it for internal routing. WireGuard interfaces, like 'tun' interfaces (as opposed to 'tap'), do not carry a Layer-2 header where MAC addresses would be; so if you have multiple peers on the same interface, the standard routing table has no way to specify which peer which packets should be sent to. Therefore WireGuard itself internally uses AllowedIPs to map each destination IP address to a single destination peer (similarly to OpenVPN's "iroute", Tinc's "Subnet", &c).
If you want a full mesh, you'll need a separate interface for each peer.
