Having successfully killed my (Centos 7) mail server I have had to build a new one. Thankfully I had a server build that I was about to start configuring as my new web server. I appear to have set everything up okay, Exim, SpamAssassin, ClamAv, Dovecot, Postgresql, httpd etc. Everything appears fine apart from when I try to connect to my web server. Whatever tried to connect suffers from a delay, and either times out or works eventually. I started off with problems connecting Exim to Postgresql on the web server. I then found that I couldn't connect using psql, or using Perl DBD-Pg. I then found I couldn't SSH or SCP, dispite them both being on the same subnet. The more I use the new system, better it appears to be, but the delay is still there. name resolution isn't the problem as I can nslookup both ways without problems, and specifying IP addresses makes no difference. For testing I have disabled the firewall and selinux and that made no difference. If I try to connect the other way there is no delay, but I cannot access the Postgresql server on my new mail server from the web server. Anyone got any ideas?