Dear @CJIT,

CJIT wrote

Installed this router and it worked for a few months at my clients office.  Then I received calls saying they had problems with their dentrix database.  Turned out to be this router.  Now it's been sitting on my shelf for over a year because TP-Link support told me to upgrade the firmware, but there is only 1 version for this revision of router (v3) 

Not sure if it helps, here is the latest beta firmware that fixed the PPTP disconnection issue. TL-R600VPN(UN)_V3_20180207_Beta