I am trying to setup on premise builder with github enterprise integration.
Everything seems to work until I attempt to sign in.
After signing in to github enterprise I am redirected back to my builder instance and then I see a call in DevTools Network tab to/v1/authenticate/<state> and a response of {"code":7,"msg":"406 Not Acceptable- "} and an http status of 401
Would it be possible to share the OAUTH_* env vars you used to configure your on prem builder instance? Redacting any secrets of course 
IIRC, the Github Enterprise API has a slightly different prefix than public GitHub, but it’s been over a year since I’ve worked with an instance of it. The one item that would jump out at me is the OAUTH_USERINFO_URL, which I think will a route prefix of api/v3 (EX: https://your-ghe-instance/api/v3/user )
#!!)(@!&
I missed the /api/ before v3
fwiw
export OAUTH_USERINFO_URL=https://<your_github_enterprise_host>/api/v3/user
export OAUTH_AUTHORIZE_URL=https://<your_github_enterprise_host>/login/oauth/authorize
export OAUTH_TOKEN_URL=https://<your_github_enterprise_host>/login/oauth/access_token
export OAUTH_REDIRECT_URL=https://<your_builder_host>/
Thank you!