Error 503 - Service Unavailable

When I try to access the dashboard or simply browse a local site, I receive the error 503.
To keep going, I have to refresh several times (F5) until I finally con do it.
I am using the FlyWheel version 2.3.1 (Pre-Release) on Windows 10 - 1803 (8 Gb Ram).
Thanks a lot.

Service Unavailable
The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.

Don’t know if you ever got this fixed but if not:

If you are using Apache then try going to the “Site Setup” tag on the site’s dashboard you are having an issue with, then click “Change”, and set the server to NGINX.

I read this from another post on here and it helped me.

Changing the server to NGINX cause any problems when uploading website to an APACHE server?