This errors point to invalid credentials.
They both happen on account changes on the registry, or local system changes.
(Most common: Switch from wireless to wired connection or back.)
The solution to fix this, is to delete the saved login, and reuplink, to update the saved credentials.
Step 1, to remove the saved credentials click on the red X in the top right corner of the server-list.
Afterwards, click on the button left of the position the X was,
and enter your registry login, as you would on the registry site.
You should be able to connect to servers again after this.