EDIT:
I went for it and installed the intermediary then the latest, gave an error. I installed the last link (R10), then to R14, and it worked. Thank you!
Original:
Understood. To clarify, I should still follow the steps outlined in the OP? I had no issues installing the closed beta firmware R13. Just making sure I'm following the right steps from closed beta R13 -> R14 open beta version.
Intermediary firmware first.
https://www.dropbox.com/s/hpeb2w2m4mvmv3q/INTERMEDIARY_FIRMWARE.img?dl=0
Then the latest firmware.
https://www.dropbox.com/s/n5nk0fxkhzosvp2/XR500-V2.3.2.134-dumaos33-rc14.img?dl=0
If issues, use that last link in the OP. Right?
To update to R14, you can just download the new firmware from the Dropbox link and upload it from the DumaOS update page. Checking for new firmware only checks with Netgear servers I believe, not Netduma.