I'm trying to create an OpenVPN connection to an old IPFire but the generated client config doesn't work with the server.

#OpenVPN Client conf
tls-client
client
nobind
dev tun
proto udp
tun-mtu 1400
remote a.b.c.d 1194
pkcs12 test.p12
cipher AES-256-CBC
auth SHA512
verb 3
ns-cert-type server
verify-x509-name a.b.c.d name

a.b.c.d is the public IP of the IPfire. It should give an address on a dedicated OpenVPN subnet when connected but complains it needs a gateway parameter and ifconfig.
Adding
route-gateway <address of dedicated subnet here>
gets me a bit further. Adding an ifconfig with both addresses on the dedicated subnet gives:
The local and remote VPN endpoints must exist within the same 255.255.255.252 subnet.
The dedicated subnet is .242 What should I put in the route-gateway? TFM isn't giving me much of a clue.

It turned out the OpenVPN subnet wasn't large enough. I tried it when no one else was connected and it connected fine with the original config. Not sure what was using all the addresses, though as it only had a couple users.