3 John 1 10
So when I arrive, I will call attention to what he is doing, his boiling over and casting malicious reflections upon us with insinuating language. And not satisfied with that, he refuses to receive and welcome the [missionary] brethren himself, and also interferes with and forbids those who would welcome them, and tries to expel (excommunicate) them from the church.
Compare with other 3 random translations
YLT 3 John 1:10because of this, if I may come, I will cause him to remember his works that he doth, with evil words prating against us; and not content with these, neither doth he himself receive the brethren, and those intending he doth forbid, and out of the assembly he doth cast.
EAS 3 John 1:10So, when I arrive there myself, I will speak to the believers about this. I will tell them clearly about the bad things that Diotrephes is doing. He tells other people bad things about us that are not true. Even that is not enough for him. He himself refuses to welcome the believers who are visiting. He also stops anyone else who wants to welcome those visitors. Instead, he sends them away from the group of believers.
NAS 3 John 1:10For this reason, if I come, I will call attention to his deeds which he does, unjustly accusing us with malicious words; and not satisfied with this, he himself does not receive the brothers either, and he forbids those who want to do so and puts them out of the church.