Password not recognized on satellite RBE970

does  power cycle of the RBR and RBS get the password set on the RBS from the RBR?

Try turning off the RBS. Remove the RBS from the RBRs web page. Power ON the RBS and press the reset button unit the back LED turns red. Release set button. Wait about 1 -2 minutes and re-add the RBS using the RBRs Add Satellite feature on it's web page. Follow instructions. Might have the RBS in same room as the RBR while you do this. 

Sorry for the delay, I was traveling.

Thank you for your feedback. Unfortunately, I've tried everything :(

For various reasons, I can't connect the Orbi devices directly to the internet. So I'm using my local Linux PC.

I started from scratch, with the RBR and the two RBS devices on my desktop:

1. Factory reset of the RBR
2. Wi-Fi connection from my Linux PC to the RBR at 192.168.1.1 (obtaining an IP address of 192.168.1.38 for my PC)
3. Factory reset of the two RBS devices, then waited a few minutes : the two RBS devices were automatically reattached to the RBR (at 192.168.1.38 and 192.168.1.82.

I then want to manually update the RBS devices using files downloaded from the Netgear website.

On the manual update page, when I check the box corresponding to the first RBB and click "UPDATE," a popup appears with the URL 192.168.1.138 of the first RBS, asking for my login/password.

Can you confirm that it is indeed the "admin" / "password" combination?

An important point: due to a bug in the firmware I'm currently using (9.12.2.1), I had to bypass the step involving the two security questions at the beginning of the RBB setup by opening a new tab and "patching" the step number.

I contacted Netgear support at the time, and they confirmed the existence of this bug and that there was no other way around it.

Therefore, I never had to provide a password ! That's why I'm asking about a default password...