Well, the AC2600 is just a WiFi speed classification, which many OEMs use and also use in device names or in addition to them. But R7800 was actually nighthawk X4S (R7800) if I remember right.
https://www.amazon.com/Netgear-R7800-100NAS-Nighthawk-Ethernet-Compatible/dp/B0192911RA
Ps. On your router's page it is said that your model exists since 2018, while R7800 has been there since 2016...
"Date First Available Oct. 20 2018"
What does the label in device bottom say????
You might have R7400?