When you create an openvpn vtun interface and set the protocol to tcp-passive it will be ignores when the client config is created:
Commands to reproduce:
run generate pki ca install ca run generate pki certificate sign ca install openvpn-server run generate pki certificate sign ca install openvpn-client set int openvpn vtun1 mode server set int openvpn vtun1 protocol tcp-passive set int openvpn vtun1 server subnet 192.168.1.0/24 set int openvpn vtun1 tls ca-certificate ca set int openvpn vtun1 tls certificate openvpn-server run generate openvpn client-config interface vtun1 ca ca certificate openvpn-client
Results in client config:
client nobind remote None 1194 remote-cert-tls server proto udp dev tun dev-type tun persist-key persist-tun verb 3 ...
it seems as proto udp is always used.