RBR750 stuck on older firmware branch – Update check returns nothing, manual file rejected

Hi everyone,

I’m running into a brick wall trying to update an Orbi AX mesh system (RBR750 router with matching RBS750 satellites) that appears completely locked to an older firmware branch.

Current State: The system is currently stuck running older firmware (router on the v6.3.x style string / satellites on v1.4.x).

The Problem:

Using the mobile app or the local web UI check-for-updates feature results in a dead end, claiming that the system is already up to date when it clearly isn't.

Downloading the official file payloads directly from Netgear's support site and attempting a manual update via the local web UI results in a rejection error stating the file is invalid or failed.

Troubleshooting steps already attempted:

Tried manual local uploads using multiple browsers with all caches cleared.

Performed factory resets via the hardware reset pinhole.

Attempted updating the satellites individually first, as well as isolating them.

Verified that the unzipped file payload matches the exact hardware model numbers, but the web UI still refuses the image file.

Has anyone run into this specific version lock where both automated checks and direct manual file uploads are completely blocked? Is there an intermediary step, a specific bridge version required to break out of this branch, or a known workaround to force the flash?

Any insights would be greatly appreciated. Thanks!