It is totally 100% server issue on exchanges or there could be some manipulation that happened during these times?
If you are oriented towards conspiracy theories, you'll always find some.
Imho it's only server issue. The software and hardware is not designed for such huge traffic and they don't invest in it just because of a couple of such days.
Just imagine:
who to buy from if the users cannot place sell orders?
who to sell to if the users cannot place buy orders?
and more important: don't you think that the trade fees in this kind of days would be huge, probably bigger than playing inside games, (and with 0 risk) if the platform would work properly?