Delay/Lag vanilla server. Delay block breaking, chest opening, door opening, etc.

I've been using aternos for about 2 years now and It's the first I've experience such thing, The delay is so bad but it's still playable if you have the patience. I'm running vanilla server (no plugins/mods) on a 1.15.1 version and there are three players ( including me) who experience lag. I have good specs on my laptop (i dont see the connection with the server) but why do we experience these lags? I really do hope you could help me fix the issue. Thanks

Quote from PaulLT

You may have bad connection or server is slow

Thanks for responding. I can assure you my internet is not the issue since I can play in other servers without lagging. What should I do if aternos server is slow?

Quote from PaulLT

Are you far or near the wifi. Try restarting minecraft

im using a lan cable directly to my router (as usual).

Quote from Mc88Donalds|Julian

try changing your software to paper

i'm scared that my world will be deleted