According to the debug logs this is related to a problem with loading /System/Library/Extensions/cpfw.kext
[ 66 2571][19 Oct 10:46:31][TR_FIREWALL] CFirewallWrapper::EnforcePolicy: firewall not initialized, calling init
[ 66 2571][19 Oct 10:46:31][TR_FIREWALL] CFirewallWrapper::Init: entering...
[ 66 2571][19 Oct 10:46:31][TR_FIREWALL] CFirewallWrapper::Init: MACOS init firewall, g_kextPath=/System/Library/Extensions/cpfw.kext
[ 66 2571][19 Oct 10:46:32][TR_FIREWALL] CFirewallWrapper::Init: CpfwLoadKext returned cpfwlib_kextload_failed
[ 66 2571][19 Oct 10:46:32][TR_FIREWALL] CFirewallWrapper::Init: CpfwLoadKext Failed with error cpfwlib_kextload_failed
[ 66 2571][19 Oct 10:46:32][TR_FIREWALL] CFirewallWrapper::Init: CpfwDiagnoseLoadKext return:
Can't stat 4/System/Library/Extensions/cpfw.kext - No such file or directory.
Deleting the site and re-creating it does not fix this problem.
Uninstalling and re-installing the Check Point Endpoint Security client (version E75.01) worked for me too and I am using a static IP (not DHCP) on my mac mini.
Note about uninstalling the Endpoint Security client E75.x and newer: Open the original DMG package you used to install the client and launch the Uninstaller shown. If you get an error message about your security settings not allowing non-appstore apps or untrusted applications from launching, hold down the Control key and then click on the Uninstaller. Selecting Open at this point will allow the Uninstaller to run.
I did confirm the uninstall removed and the reinstall did create a new /System/Library/Extensions/cpfw.kext file. I did not have to reboot but note I did shutdown the client before running the uninstaller.
However this may be a temporary fix as there is a Checkpoint Forum entry about another person who has also encountered this problem and has fixed it by uninstalling and installing but on a reboot the problem came back for them. That person tried versions E80.41 and E80.42.
Another Check Point Mac VPN Yosemite thread is reporting similar issues where some claim their client still works after a reboot but others, including the author of the above thread, who continue to see the problem return after a reboot: https://forums.checkpoint.com/forums/thread.jspa?threadID=21181&tstart=0