I’ve troubleshot a TON of those, so here are 4 things that you need to cover:
- Connectivity - as @JasonWalker mentioned port. The VMware tool uses standard https port (443) to make the connection, so check if you can connect. Launch a browser from the machine where VM Manager tool is installed and try to connect to https://{manager-host} - if you can connect, you should be good (it covers both port and hostname resolution). If either of those don’t work, you need to get them sorted… You can always do the ping & telnet tests as well, whatever you feel more comfortable with!
- Credentials - again, if you open it through a browser, it should give you the management interface and you can test your credentials
- vSphere Web Services SDK - make sure it is enabled & configured, otherwise, it will not work (full documentation)
- One last item worth noting (it took me a lot of hassle to figure out by test and trial) - in some occassions, some versions of vSphere/vCenter do not always propagate permissions correctly for users even though they are granted on the global level; I had to set the same exact permission on each hypervisor within a cluster to get it work. It is a VMware issue but nonetheless if you are banging your head against the wall, it doesn’t help you…