- check with firewall / selinux disabled and system rebooted (if you disable selinux)
- DNS / hosts file is all good
- check pbs_mom service is up and running on the compute node ( ps -ef | grep pbs_ )
- check the mom logs
- check the server logs
- check ports 15001 to 15009 , 17001 are not blocked (between pbs server and pbs mom )