When your sandbox account is transitioned to the NetSuite Domain
Once a Sandbox is refreshed, it appears that the Sandbox account now transitions from the Sandbox Domain to the NetSuite Domain (system.netsuite.com). So if you are having difficulty accessing Sandbox from the system.sandbox.netsuite.com domain, you will need to use the main NetSuite Domain. See information and links below for more information.
When Your Sandbox Account is Transitioned to the NetSuite Domain
The first time you refresh a sandbox, it is transitioned to the NetSuite domain. This changes the way users access the sandbox account.
After the refresh is complete, sandbox users must access the sandbox from the same URL that they use to access their production account (system.netsuite.com). They can use the Choose Role page, or the Change Roles list, to switch from a production role to a sandbox role.
To learn about Sandbox Accounts on the NetSuite Domain, click here.
To learn how to log in to Your Sandbox Account, click here.