How do I resolve an "ERROR 303" when running grbgetkey?

While setting up an academic license file via grbgetkey, you may receive the following error message:

error : ERROR 303: hostname <host> (<IP address>) not recognized as belonging to an academic domain
info : Is your computer connected to the university network?
info : Your computer must be connected to the university network for the grbgetkey
info : command to work. You can connect your computer either directly or via a VPN
info : that tunnels all traffic through the university network. Once the license
info : file is setup, your computer does not need to be connected to the university
info : network. You can repeat this process to get licenses for additional computers.
info : If you are unable to setup this license file, please visit our support website
info : https://support.gurobi.com for further assistance.

This error means your domain isn't on our academic domain list. To resolve this issue, please try the following:

• Make sure you are connected to your university network. If your university provides a VPN, connect to it before running grbgetkey.
• Some VPNs are configured to use split tunneling, where traffic to public internet sites is routed through your ISP.
  • If possible, try configuring your VPN client to use full tunneling, where all traffic is routed through the VPN.
  • Alternatively, ask your network administrator if the VPN can be configured to route traffic to gurobi.com through the private network.

If you followed these steps and are still receiving the 303 error, please log in to the Gurobi Help Center with your university email address and submit a new support request:

• Specify your current Gurobi usage as Academic.
• Specify the type of issue as License issue.
• Include the IP address that is being rejected.
• Let us know that you already tried the suggestions provided above to no avail.

Note: During the SARS-CoV-2 pandemic, we modified our academic license validation rules while public heath policies limited access to university campuses. We have now returned to our previous validation rules which requires users to be on an academic network to validate their licenses, so you may encounter this error when you didn't previously.

Further information

• How do I resolve an "Academic Domain Error"?
• How do I resolve the error "grbgetkey: command not found"?
• How do I resolve an "ERROR 405" from grbgetkey?
• How do I resolve the error "Communication failed" from grbgetkey?