https://paste.feed-the-beast.com/view/2c021915
forge:35.1.15
extremeSoundMuffler-3.2_Forge-1.16.4.jar

When clicking the sound muffler button, the client crashes. Apparently only when there's more than one player on the server

https://github.com/FTBTeam/FTB-Presents-Direwolf20-1.16/issues/55

Does this happens with v3.3?

i will check

This should be fixed in v3.4 if it wasn't already fixed in v3.3, fell free to comment if this is not the case and I'll re-open this issue.