The server has been updated to 1.12.1. The is some incompatibility between 1.12 and 1.12.1 and we want people to be able to use the latest version. Forge and Optifine are out. Optifine's website is experiencing issues, so you can download it here: http://optifined.net/adloadx.php?f=OptiFine_1.12.1_HD_U_C5.jar
After seven hours of searching I finally found a Jungle in the beta server. GG me.