I have the same issue, that my Guest Netwok suddenly has no password and the Orbi refuses any attempt to add one. My RBR40 claims that 2.7.4.24 IS the latest firmware, and that is what is installed.
Oops, app. I went to the web interface to check the firmware update, but forgot to try the guest password again from there. Password did set from the web interface.
Thanks for double checking. The 'app' does not have a stellar reputation on the forum. Must be really difficult to write apps for smartphones.
p.s. Orbi's Firmware Update feature on the web interface also is more complicated than it appears. In addition to the obvious grammatical paradoxes ("downloading new firmware".... then "no new firmware") the web feature is affected by Netgear's firmware release strategy:
After firmware has completed internal Quality Assurance checks (we presume) and perhaps a period of beta testing by some users, the download link to the new firmware is placed on the support web site https://www.netgear.com/support/ where users who watch the site can elect to download and manually install it. This does not cause the web interface or the Orbi app Firmware Update feature to detect it. So, "Checking for new firmware" really means, "Looking to see if Netgear is ready for me to detect new firmware." This situation can persist for quite some time. (In the case of v2.7.5.4 for the RBR50, it was released in Feb 2023 and users still report that their Firmware Update does not see it [11 months later!])
At some point, Netgear does (something?) and Firmware Update detects the new firmware and users who happen to use the feature can decide to install it.... or not.)
At another point, Netgear does (something else?) and any time the user opens the Orbi app or the web interface an announcement greets them, "New Firmware Available!!!", which they can still ignore. Users who never open the web or app, of course, are blissfully unaware.
Finally, Netgear can decide, "It's time" and silently install the new firmware in the middle of the night.
In a way this process makes sense. Testing may not reveal every possible coding error. Better to let "early adopters" find any remaining flaws. Users who are happy with their systems do not go looking for new firmware. Perhaps the 'improvements' apply only to certain users. etc. etc. In another way, it seems strange that new firmware could remain in limbo for months and months.
Anyway, good that the guest WiFi now has a password.
