Help weird latency lag thing?

so basically my friend is lagging in the server whenever we grind together. he's lag is like that he lags back and be like 1-3 mins behind the actual stuff that is happening. on his screen he's doing the class skills but its not casting and like 1-3mins later it casts. but everyone else around him is perfectly fine and can see him cast stuff although he's casting the spells will looking at ground, the wall or just standing still. and this lag makes his game experience terrible

 

The new update does lag the server quite a lot. My game just crashed because I was running using RiftWalker with Time Dilation in Detlas Suburb jn as I'm typing this comment rn :P