Roonbridge on Linux doesn't seem to recognize Wireguard network interface

I’ve been experimenting with RoonBridge over a Wireguard VPN connection so that my local audio devices are recognized by a RoonServer on a remote network.

I’m running Wireguard with the exact same configuration on three different machines:
– My MacBook Air under MacOS Monterey 12.6.3
– An old MacBook Pro under Ubuntu Linux 22.04.1
– A Raspberry Pi under DietPi v8.13.2.

The configuration for Wireguard is exactly the same on all three machines (different IP addresses of course).

All three machines are running RoonBridge 1125.

However, this setup only works under MacOS. From RoonBridge_log.txt on that machine:

02/01 17:58:12 Trace: [ipaddresses] FOUND lo0
02/01 17:58:12 Trace: [ipaddresses] FOUND en0
02/01 17:58:12 Trace: [ipaddresses] FOUND utun7

Neither of the Linux machines seems to recognize the Wireguard network interface (called wg0 there, not utun7 as on the Mac):

02/01 18:01:03 Trace: [ipaddresses] SKIPPED lo: not up
02/01 18:01:03 Trace: [ipaddresses] FOUND eth0
02/01 18:01:03 Trace: [ipaddresses] SKIPPED wg0: not up

This is from the DietPi, but the Ubuntu machine behaves the same. Interestingly, on both machines RoonBridge also claims that the local interface isn’t up.

On the remote RoonServer, this results in the following lines in the server logs:

02/01 19:14:42 Trace: [SOOD] Adding User IP
02/01 19:16:27 Trace: [SOOD] Adding User IP
02/01 19:16:27 Trace: [SOOD] Adding User IP
02/01 19:16:27 Trace: [SOOD] Adding User IP
02/01 19:16:27 Trace: [SOOD] Adding User IP

The first line is my MacBook Air’s Wireguard interface, the second its local ethernet interface. Then there are the DietPi’s and the Ubuntu machine’s local ethernet interfaces. Their Wireguard tunnel interfaces don’t show up. The last line is the server itself.

Of course the server doesn’t know how to connect to any of the remote IPs (on the subnet), only those that reside in its own subnet. Which means it can work with the MacBook Air’s Wireguard interface, and it finds any endpoints connected to that, but not with either of the Linux machines.

Which brings me to my question: What needs to be done to have Roonbridge acknowledge the wg0 interfaces that it currently skips on the Linux machines?