Rbk50 can’t connect to nbn arris modem

Doesn't tell us a whole lot.

1. Whats failing? details help not just it won't connect. Its like me calling my mechanic and saying "my car doesn't drive, tell me whats wrong?"  

2. What firmware is on your orbi?

3. Are you trying to set via hardwired connection, app, wireless? Whats happening?

4. if you direct connect to  your modem, does it work?

5. The arris cm8200 has 2 ethernet ports but only 1 works. Make  sure you're plugged into port 1

Many times to fix the problems do this:

1. shut off both router and modem. disconnect all devices from both. 

2. power on the modem. give it a couple minutes to fully boot. 

3. Connect port 1 on modem to wan port on router. *Don't connect anything else to modem even once setup*

4. Boot up router. Give it a couple minutes to fully boot.

5. Connect to router with 1 device and try to go through setup.

did it work?