RBK50 no internet with Spectrum Modem

Hello, I recently made an internet provider switch and I need some setup help with my Orbi. I previously had AT&T Uverse with a cable modem. Out of the cable modem, I directly hooked up my Orbi router and ran wireless network "Orbi". Everything went smoothly. I recently changed from AT&T Uverse to spectrum as an internet provider. Spectrum installed a modem only, a DOCSIS 3.1eMTA. We got that set up, and verified we had internet by running a wired line from the modem to a desktop computer. I hooked up the Orbi, and had no internet connection. I them fully reset the Orbi, went through the entire reset process again, but still had no internet connection showing in the setup app. So, Spectrum installed their router, a RAC2V1S maybe by Sagemcom? I was able to hook devices up to that wireless network, "Spectrum", and had internet connection. I plugged in the Orbi, and had internet connection show up in the setup. So, shows internet connection when flowing from modem through Spectrum router to Orbi, but no internet when wired from modem to Orbi.

So, can someone please help me figure out the right steps to take in order to get the internet going directly to my Orbi without the need for another router in the middle?

Because, even though the Orbi says it has an internet connection when wired to the Spectrum router, many websites and other functions will not work (acting like no internet connection present) but others do. I suspect I would need to set up the Spectrum router as more of a passthrough... But since I want to eliminate that router, I'm not sure I need to troubleshoot that issue yet.

Many thanks for any help! I had been hoping for a simple switch out of equipment... I guess that was a silly dream :)