My cable modem got fried so the cable company (Spectrum) gave me a new modem (looks identical, but now has a 2.5G Ethernet port). I have lots of Deco M9's (long house), and have tried them all for the main setup. Every time I go through the connection process, the app finds the deco and starts to set it up, but then turns red when testing the internet connection. Nothing works - I have tried rebooting the world numerous times. The internet and modem are working, as I can connect my computer and Tv to the modem without issue. My question is whether this new modem is not compatible with the M9. Any idea would be most appreciated! 
 

Modem is Spectrum ET2251 (I think it is hitachi).