Friend server connection problem

My friend just bought the game and we cant play in each other servers, keeps getting connection errors when we try to connect. However, we could join in someone else server, but thats not how we want to play. 

We are trying for a few days, and nothing changes. We play other games together, so we dont believe it is an Xbox Live issue. I am wondering if it is an internet connection issue, specially for the server host. We live nearby and have the same internet company, could it be the reason? Or, is there a minimum ping to host a server properly?

We need that to be solved as soon as possible, otherwise he would apply for refund. I ended up by convincing him to buy the game because I really like it, than we would be able to play together. However, we are not.