How to set a universal Time setup in moment.js for client in different region

Let’s say I have a client A in (-6 UTC) Timezone. I have Another Client B in (+6 UTC) Timezone. My server is in (+3 UTC) Timezone.

Sample Case: Let us imagine we have a system having Blog feature. And Client A has written a blog in 13:20:00

On the other hand, Client B is in (+6 UTC) timezone. Now he should see Client A has posted few seconds ago .

Same goes for the vice versa. If Client B writes an article in 14:00:00 (+6 GMT), and after 2 two hours, Client A should see Client B has posted two hours ago , although he is in (-6 GMT)

Now How do I setup moment.js for system mentioned above?

I believe this is what ure looking for: