Realms for users don't work after a wile playing

I was playing in the server of my friend with my first account "Elfeliscatus" after walking 3 hours in the minecraft world I die an respaw (normal) then I stop playing and the nex day I couldn't go in in the server again.

So I create another account name "Elfeliscatus 2", and start playing in the realm normally but after playing one day stops working again and Stops working for like 2 hours. And this just happens to me in the server.