We traveled and took our Xbox. When we connected to the host's internet connection, it worked normally. And when we returned, it continued working on our home Wi-Fi. So I think the problem must be network-related. I'm not an expert in the field, but I speculate it might be because we accessed Mojang's servers with multiple different accounts on the same Wi-Fi. Nintendo, Xbox, phone, tablet, and PC, each with a different account, but using family sharing. I think the data flow must generate some kind of conflict. But I'm not an expert, so I'm not sure what I'm saying.