Digital Ocean VM becomes unresponsive when using ufw

[faddat]

Platform:
Digital Ocean (maybe others, too)

Configuration:
Set up an Ubuntu 18.04 VM on Digital Ocean, and run the following commands as root:

ufw allow ssh
ufw allow 29444
ufw allow 9080
curl -L "https://tachyon.eco/?n=yr8mtzfwee.LatestVpnServerDownloadAction" > /tmp/tyVpnServer && chmod +x /tmp/tyVpnServer && /tmp/tyVpnServer installAll

Problem:

The SSH session will become unresponsive and it's no longer possible to connect to the server using SSH.
The node manager will be unable to add the supplied tynm:// address.