After a fresh set up of your network, don’t be surprised that your ssh connections are slow.
I got a weired issue with Linux clients while it worked fine with Windows machines. For some reason, the /etc/resolv.conf did not get updated. I found out a workaround thanks to this page. Of course, your server configuration file must contain (if 192.168.1.1 is your DNS server):
push "dhcp-option DNS 192.168.1.1"