There are often cases when a player can't break-free from stuns.
The character is just repeating break-free animation multiple times in row, even with CC-immunity animation already swirling around, yet the stun doesn't break.
Stun locking is a thing in PvP for many years already and only getting worse.
I guess you can't even fix it anymore with such amount of CC abilities and sets.
Also, client side connection or hardware is not the issue, don't even start with that.