Using network interface altnames doesn't work

[hashworks]

My main network interface has two altnames:

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether redacted brd ff:ff:ff:ff:ff:ff
    altname enp0s25
    altname eno1

When I run a vopono session using -i eth0 it works just fine, but with the altnames -i eno1 or -i enp0s25 it doesn't (network connections just timeout).

Seems to be because the iptables forwarding expects the main interface name.

I guess this behavior should be documented.