if you're on the free license, FREE license does not allow you to use the serial port connected over network!
Can't find this information nowhere on VMWare website or otherwise. If you find a link states this, please reply to this.
So the solution: You need to go back to the evaluation license for valid for 60 days.
However, clearing the license from Web Client was not enough. Because it didn't go back to Eval license. It stayed kind of empty. (In 6.7 go to Host > Manage < Licensing > Remove License)
So I tried to enter the Eval licsense. Eval license is all zeroes. However, web client doesn't register the license to 00000 for some reason. It seems like it accepts it but do not register.
I had to do this:
Connect via SSH. Then:
vim-cmd vimsvc/license --show
vim-cmd vimsvc/license --set=00000-00000-00000-00000-00000
vim-cmd vimsvc/license --showthen you can connect with serial over console.