So you cannot join any server, no matter what?
what servers did you try to join?usually your two issues as stated in the topic title are separate.
Seems to me like a firewall issue.Try turning it off and see if that helps.
The manifest download can take a while when you join a server that has lots of addons you don't have. How long did you wait each time? Sometimes you just have to be patient.
For me when download manifest stops I tab out of blockland (I play full screen) and when I go back to it it will update showing the amount that has loaded.
Try deleting your cache database and retry.
No result unfortunately =\
Post a console.log
Make sure you turn on your firewalls againPlease do this tooChances are it could be your router blocking ports