Port 993 won't open on IPv4

I’m trying to get Dovecot to work on Port 993 on IPv4. For some reason it’s working fine on IPv6.

In the 10-master-conf I have:

service imap-login { inet_listener imap { #port = 143 } inet_listener imaps { port = 993 ssl = yes }

Number of connections to handle before starting a new process. Typically

the only useful values are 0 (unlimited) or 1. 1 is more secure, but 0

is faster. <doc/wiki/LoginProcess.txt>

#service_count = 1

Number of processes to always keep waiting for more connections.

#process_min_avail = 0

If you set service_count=0, you probably need to grow this.

#vsz_limit = $default_vsz_limit
}

service pop3-login {
inet_listener pop3 {
#port = 110
}
inet_listener pop3s {
port = 995
ssl = yes
}
}

In theory shouldn’t it open both a port on ip4 and ip6?

Operating system Debian Linux 8
Webmin version 1.872
Usermin version 1.734
Virtualmin version 6.02-3