A host will not enroll or check in

What the host installer's messages mean, and what to check when a desktop stays at Never checked in or goes Offline.

The installer stops with a message

Setup says	What to do
The portal address has to start with https://.	Type the portal's address with `https://`, and no path after the name.
An enrolment token is needed: the console makes one under Deployment, Enrollment tokens.	Make a token and paste it. See Register a desktop and create an enrollment token.
The portal address, the token and the direct address cannot contain spaces or quotes.	Check for a stray space at the start or end of a pasted value.
0.0.0.0 is an address to listen on, never one a client can dial.	Leave the direct address empty, or give the address people's computers reach this machine at.
Installing the stats agent, which enrols this host, failed (exit n). The host agent was not installed.	The portal refused the enrollment, or could not be reached. The message includes the stats agent's own log: read its last lines, then see below.

Setup changes nothing when enrollment fails, so you can fix the cause and run it again.

Check, in this order:

The token is fresh and unused. Each token works once and expires after a short time. Make a new one and try again.
The machine can reach the portal. In PowerShell on the machine:
```
Invoke-WebRequest -UseBasicParsing https://portal.example.com/_health
```
It should return status 200. If it fails, check DNS, the firewall's outbound HTTPS, and any web proxy.
Nothing is intercepting HTTPS. A security product or proxy that replaces certificates breaks enrollment. Exempt the portal's name from inspection.
The machine's clock is right. Certificates are checked against it.

The machine enrolled but its agent is not reporting:

On the machine, open Services. Billet stats agent and Billet host agent should be Running. Start any that are not.
Read the agents' logs in %ProgramData%\Billet\logs.
Check the machine can still reach the portal, as above.

The machine is off, asleep or restarting. Hosts should not be set to sleep.
The Billet host agent service has stopped. It restarts itself after a crash; if it keeps stopping, its log in %ProgramData%\Billet\logs says why.
The machine lost its network, or its route to the portal.

Another remote access agent on the machine may be capturing the screen. Two capture agents on one machine compete for it. Remove or disable the other.
Update the GPU driver, then restart the machine.

If none of this helps, collect logs and contact Billet support.