Moving to new server

I’m fairly new to Gitlab. I have a server instance with about 400 projects. I need to move it all to a new computer. The backup commands I’ve found on the internet so far have not worked. I’ve tried both of these without success:

use this command if you’ve installed GitLab with the Omnibus package

sudo gitlab-rake gitlab:backup:create

if you’ve installed GitLab from source

sudo -u git -H bundle exec rake gitlab:backup:create RAILS_ENV=production

gitlab-rake isn’t found and the rake command doesn’t execute in the second one.

What is the most straightforward way to move my Gitlab instance to the new server? It is about 20GB of data.

Thanks, Derek