How to login arcgis server admin directory ( not arcgis server manager )
option 1. use arcgis server admin account to login
option 2. for federated server, you can generate portal token login without arcgis server admin password.
https://gis1.victorvilleca.gov/arcgis/admin/
Home, Click machine, you will need machine full name when you install arcgis server web adaptor,
Check whether your arcgis server windows service is running