I have a CRM on a server on a network. We have a static IP and another server outward facing. We use port-forwarding to map to the CRM, so that when you go to the IP or the FQDN, you get to the CRM:

xxx.xxx.xxx.xxx

crm.example.com

Internally, we can access the CRM by going to

crm

or

crm.example.com

Lately, I've been noticing that accessing the server from outside the network times out or gives 503, bad gateway. During that time, I can also SSH (different port, so this works) into the outward facing computer and access the server just fine.

I have a robot monitoring the site and indeed via HTTP monitoring the site is going down periodically.

I looked through the Apache server access and error logs and nothing stuck out at me so I'm a bit confused as to what could be going on. I also searched the access logs for 503 and found nothing.

When I run tracert from outside the network, it appears the packets basically make it through the wider area servers (Comcast city and county servers) and end up dropping at the CRM server's front step.

I'm tempted to replace the server because it is older and underpowered but it would be nice to know what is going on.

Any ideas what to do next?