Server starts lagging after 5 or 10 minutes after I entered, and stops working after, kicking all the players on it

Well, I ve started to play Pixelmon with my 2 friends, and we were good on the first 2/3 days. But then, I entered and for 1 hour I was good, but when my friend enters, the servers starts do get laggy, and then it stops working, kicking all the players showing a message , that i dont remember, but yeah, this is it. And, since that first happen, it happens all the time more than a 1 person is on a server. What can it be? I mean, it cannot be overload servers, i went when only 200 people were wondering for a server. Now it was more, 1200, but the other day nope. Thanks if someone helps.

And it happened again... My friend was in the server, I entered and the server starts lagging and stops

Yeah, pritty much it, after 5 to 10 minutes it starts to lag and then we got kicked. Or otherwaise, the reverse, he is at the server, and I enter, and then the server goes down. Just a couple of days ago it started to happen. What is this? Can you help me? Thanks

nah, if the first days were fine, i dont see that to be the reason of the problem