This video teaches you how to fix 503 Unavailable Service error when trying to connect to vSphere Web Client. Please note that use PuTTY with caution -- please do NOT try to abuse PuTTY and please review the site's LEGAL WARNING first!
Useful posts:
https://kb.vmware.com/selfservice/mic...
http://davidcocke.blogspot.com/2012/0...
http://davidcocke.blogspot.com/2012/0...
http://blog.ukotic.net/2015/06/14/ena...
https://virtualizationreview.com/blog...