Wow, I just read that VMware KB article, and that's terrible! I have to say that VMware quality control seems to have been slipping as of late. On ESXi 5.0 we encountered "purple screens of death" (PSOD) with certain Linux guests, and now we have this networking problem. After 5.5 was released, I was planning to re-evaluate ESXi 5.x, but I guess I will hold off on that. 4.1 has always been rock-solid for us, and we will continue to stick with that for the time being.
Anyway, I also found this discussion thread at VMware's site:
https://communities.vmware.com/thread/4 ... 5&tstart=0 -- it sounds like the problem is that GRE packets are not making it to the guest. This would explain why it affects all PPTP traffic regardless of what the guest is (it doesn't just affect MikroTik, or other Linux-based systems).
Just to clear something up, I don't believe that VMware is dropping support or deprecating the non-paravirtualized interfaces (e.g., e1000). I believe that this is an honest-to-goodness bug that they will get around to fixing...eventually. Probably in 5.5u1. You can see in the discussion thread that VMware support techs are continuing to collect information from users about this bug even after publishing that KB article. Also, switching to VMXNET3 doesn't completely solve it: the last post in that thread explains that if you run a PPTP client in the guest, it still has problems; switching to VMXNET3 apparently only fixes PPTP servers, somehow.
So my advice would be to downgrade to 5.1 (or even earlier) until this is fixed in an update to ESXi.
-- Nathan