As you may have read in other threads, this version of Lemmy (0.19.1) seems to have bugs in outgoing federation on some instances.
As a temporary fix, we have added a scheduled restart of Lemmy every hour. It only takes a few seconds to restart, and the big advantage is that your comments and posts are only delayed up to 1 hour before they federate to other instances. You probably wont notice the restart even.
This will be in effect until a bug fix arrives from Lemmy developers, probably after new years sometime.
Thanks for reading and merry x-mas to everyone. :)