v0.4 fails with “Address not available”

[PromyLOPh]

Since v0.4 chatmail-turn fails to start with this error message:

Listening on 172.31.1.1
Error: Io(IoError(Os { code: 99, kind: AddrNotAvailable, message: "Address not available" }))

There is no such address configured on this server, however ip shows the following:

# ip a
[…]
2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
	[…]
    inet […] peer 172.31.1.1/32 brd […] scope global ens3
       valid_lft forever preferred_lft forever
[…]
# ip route
default via 172.31.1.1 dev ens3 onlink
172.31.1.1 dev ens3 proto kernel scope link src […]

This is a virtual server at Hetzner.

v0.3 works fine.