I appreciate your input and time to respond to this problem!
I did some further investigation based on your thoughts of likely DNS problems:
1) – PING worked fine on all external IPs
2) – DNS lookups failed at the given variable time frame (1+ hour(s))
I concluded that the added DNSMASQ was the likely problem – as it does both DHCP + DNS caching and lookups. As I run a dedicated server with a fixed IP and its own hosted / dedicated [nameserver], I changed the following DNSMASQ configuration as per:
This change was made some 5 hours past, and so far all my ISPConfig based Server out-bound HTTP requests from the Server are completing (no 404 errors).
I conclude that the DHCP lease / expire times of the original dnsmasq were the problem, and I certainly only wanted DNS caching – and not DHCP.
Based on some other users thoughts and experiences, I finally decided to use PDNSD (proxy DNS cache). This works fine, and does offer good outbound DNS caching, even across server restarts.
Thanks for creating ISPConfig 2 and 3 – I have used them both and they are both great products. Very different in each V2 & V3 version, but well programmed!
Peter Bowey Computer Solutions
69 Sutherland Ave, Hayborough,
Victor Harbor, SA, Australia, 5211
Ph: (08) 8552 8630
Fax: (08) 8552 9185
Mobile: 0414 440 575