It can be upgraded directly to v4.9.1. There is no need to upgrade to v4.9.0 first.
It's fine to upgrade through either the Admin Panel or the GL.iNet Download Center.
As a precaution, we recommend exporting a configuration backup before upgrading so that you can roll back if any issues occur. Please follow this guide:
Please also note:
v4.9 includes some changes that may require you to review and adjust your configuration after the upgrade. Please refer to the following release notes: