Can't connect? Having any weird issues? Check this out!
(Will be expanded as needed.)

No sound

First try just restarting the game a few times - sometimes that's all it takes. If that doesn't work, proceed:

Download this (in gzip format, you will need 7zip or similar to extract): https://archive.org/details/Beta-1.7.3

In MultiMC/Prism, click on your b1.7.3 instance and click "Folder" on the right side menu. Enter the .minecraft folder, delete the contents of the resources folder there, and replace them with the files from the extracted archive.

Can't connect

This includes timeout errors, "An existing connection was forcibly closed by the remove host", and similar. First, make sure you're using either Prism Launcher or MultiMC. The official launcher does not handle old versions as well.

When you made your instance, make sure you selected b1.7.3 and NOT 1.7.3. This requires toggling the "Betas" checkbox seen below.

Finally, try connecting to the website - if you can't visit that, there is a chance your ISP may be blocking our IP address. DM me and I'll help.