Smiinx

So, my friend has this server that we play on, and we decided to update it to 1.17, but it was super laggy so we decided to change it back to 1.16.5. Now, whenever we do the /join code, it sends us to a new hub. None of us can get in, and we do our join code, and boom, were just in a new joining hub. if anyone knows how to fix this, it would be much appreciated if you told me, tysm!