Re: If this is software post-sales support, I don't fully understand.
And by support you mean confusing replies?
offsite support ussually means "I want to connect to the machine and play with it", at least in my experience, and I understand the reasons behind that, they cannot divine the problems,
Many companies and org have spent good money making sure the servers are not accesible from outside, so quite logically are unhappy with people from china connecting. Or from elsewhere.