My girlfriend, my friends, and myself are trying to play together on Bedrock Edition. Two of us have PCs, one has an Xbox, and she has a Nintendo Switch. When those of us on PC or Xbox try to host a world, she can't join it, she just gets "Unable to join world" with no error code after it tries to locate the server for 10 seconds. However, when she hosts the world everybody else can join her for some reason.

She has Nintendo Online still, Her NAT type is B, and her upload/download speeds are at 8.7/38.3 respectively. Her and I even play on the same Wi-Fi and I have no problems connecting to her world. I think this might be a bug in the Nintendo Switch version of the game or at least a few of them. I've reached out to every possible guide and troubleshooting option and they all yield no result. Restarting the router, port forwarding her, changing her DNS, etc. Thank you for looking into it as a possible bug.