# This works
> sudo OPENSSL_ENABLE_MD5_VERIFY=1 openvpn --daemon --user piotr --config /etc/openvpn/xxx.conf

# `sudo journalctl`
(...)
Mar 22 21:45:08 demon openvpn[31225]: VERIFY OK: depth=2, (...)
Mar 22 21:45:08 demon openvpn[31225]: VERIFY OK: depth=1, (...)
Mar 22 21:45:08 demon openvpn[31225]: VERIFY OK: depth=0, (...)
(...)

# This does not work
> sudo systemctl start openvpn@xxx

# `sudo journalctl`
(...)
Mar 22 21:51:47 demon openvpn[31587]: VERIFY OK: depth=2, (...)
Mar 22 21:51:47 demon openvpn[31587]: VERIFY ERROR: depth=1, error=certificate signature failure: (...)

(...)