New MB7621 Modem + Orbi Mesh - cannot get to work

Finally had it with my Netgear C300 which is giving me wireless speeds of 25-50MBS on a 300MBS plan (wired gets over 200MBS)...

First had Comcast technician out...replaced the line from the pole to the house...confirmed the splitter (one line to modem, one to tv) was good...and they found a "node issue" in the neighborhood that was fixed the next day.  This helped my wired speed be more consistent, but didn't do much for wireless.  Another phone tech said my modem details were not registered with Comcast, so I gave them the MAC/SN/TA.  Not sure anything really changed - maybe the wireless speed is more consistent in the 20+ range (there were many times it would be <5MBS!).

Anyway, new MB7621 (Motorola) modem works ok wired - close to 300MBS - BUT first sign of an issue is that the browser locks up for several minutes after the speed test.

Moved on to trying to connect the Orbi mesh router...and after pairing with the satellite (which oddly takes multiple attempts with the satellite 10 feet away) - there is no Internet connection.  Did this multiple times - resetting modem each time, etc.

Decided to pay for two internet connections temporarily so I can work with the new modem without having to keep registering old/new back and forth (I need the wifi for work, so when I can't get it working, I have to go back to the Netgear, re-activate, etc.).

Had hoped these two devices would just be plug-n-play - but clearly I am doing something wrong (or there is something wrong somewhere and I can't figure it out).

Appreciate any help.  Thx