Running short of concurrent connections
 

2012-12-20 09:26:35.007 NOTICE [212.33.109.197:58679-0#APVH_domain.com] Current available connections: 0, real in-use: 5000
2012-12-20 09:26:35.007 WARN [117.252.18.99:63781-0#APVH_domain.com] Running short of concurrent connections.
2012-12-20 09:26:35.007 NOTICE [117.252.18.99:63781-0#APVH_domain.com] Current available connections: 0, real in-use: 5000
2012-12-20 09:26:35.007 WARN [118.71.162.89:36351-0#APVH_domain.com] Running short of concurrent connections.
2012-12-20 09:26:35.007 NOTICE [118.71.162.89:36351-0#APVH_domain.com] Current available connections: 0, real in-use: 5000
2012-12-20 09:26:35.108 NOTICE Resume All Listeners
2012-12-20 09:26:35.109 WARN [37.150.80.225:38395-0#APVH_domain.com] Running short of concurrent connections.
2012-12-20 09:26:35.109 NOTICE [37.150.80.225:38395-0#APVH_domain.com] Current available connections: 0, real in-use: 5000
2012-12-20 09:26:35.109 WARN [178.90.252.67:56854-0#APVH_domain.com] Running short of concurrent connections.
2012-12-20 09:26:35.109 NOTICE [178.90.252.67:56854-0#APVH_domain.com] Current available connections: 0, real in-use: 5000
2012-12-20 09:26:35.109 WARN [223.144.13.133:15043-0#APVH_domain.com] Running short of concurrent connections.
2012-12-20 09:26:35.109 NOTICE [223.144.13.133:15043-0#APVH_domain.com] Current available connections: 0, real in-use: 5000
2012-12-20 09:26:35.168 NOTICE Resume All Listeners
2012-12-20 09:26:35.169 NOTICE Resume All Listeners
2012-12-20 09:26:35.169 WARN [79.135.76.200:44227-0#APVH_domain.com] Running short of concurrent connections.
2012-12-20 09:26:35.169 NOTICE [79.135.76.200:44227-0#APVH_domain.com] Current available connections: 1, real in-use: 4999

What is the problem?

you set max connections to 5000, but all used up.

maybe are your server under ddos attack ?
or the server is very busy ?

My server is protected from ddos attacks as i sit behind the firewall.

Is this just a problem with the settings?

A firewall does not necessarily protect you from ddos attack. Really depends how it is setup. In your case, there are over 5000 concurrent connections which exceeds your current max connections settings in LSWS. hence the message. You can increase the limit to 10000 or higher in LSWS (Server => General) and see if the similar message again.

You may follow the guide below to help the situation if there are excessive connections from individuals (possible ddos attack).
http://www.litespeedtech.com/how-tos.html#qa_dos