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Just got off the phone with Comcast after a few hours, and they suggested I go straight to Netgear for help with my R6400v2 router.
I had a CM700 modem, but my family upgraded to a gigabit connection on account of everyone working/schooling from home, so today I bought an Arris Surfboard CM8200 modem and got it activated through Comcast. However, my R6400v2 wouldn't detect the internet connection coming from the new modem, even though I could connect to my PC directly from the modem. Eventually, after doing a factory reboot on the router, Comcast came to the conclusion that the new modem and the old router were incompatible.
Since I still have to work from home tomorrow and my kids have their online classes, I had them reactivate my original CM700. Like the new modem, it works fine when connected directly to my desktop PC, but now the router isn't detecting a signal, same as with the new modem.
Every time I connect through the router and go to routerlogin.net, it spends some time trying to detect the connection, and ultimately fails. It asks me to cycle the power (which I have done dozens of times, both on and off the phone with Comcast) but it never works.
I'm stressing out because my kids use school-issued Chromebooks for class, and neither one has a way to connect via LAN. At this rate, they're definitely going to miss at least one day of school. I just want to see if there's anything I can do for my router before I give up and buy a new one. Thank you!
Factory reset both the modem and the router. Push and hold reset for 7-15 seconds while their powered on.
After the reset. power both down and disconnect everything from both (including coax)
then connect coax back to the modem and power it on. give it several minutes to fully boot.
Then connect a known good ethernet cable from modem to wan port on router.
power the router on, give it several minutes. Attempt setup.
With the Arris CM8200 you can follow the same procedure. just make sure that nothing else is plugged into the modem. Only have the netgear router connected to port 1. leave port 2 empty. It has 2 ports but only 1 port can be used on it with spectrum, cox, xfinity. that other port is only useful if you have wan port aggregation (R6400 doesnt') or if your isp supports multiple public ip address (most isp's dont support this)
Did you try upgrading the firmware on that router to see if that fixes the issue? Also can you just use your router with the current working modem until saturday so you can retry making it work that way your kids don't miss out on school. I see that the cm700 works up to 500mbps which gives you enough bandwidth for everyone for the time being.
I'm sorry if I was unclear in my original post. Both modems work, but currently the Netgear R6400v2 router does not work with either one. It was fine with the old modem until I did the factory reset yesterday, and now it won't detect the internet connection at all.
I can't even log into the router, because it tells me there's a problem connecting to the internet, so I don't even see an option to update the firmware or anything.
Factory reset both the modem and the router. Push and hold reset for 7-15 seconds while their powered on.
After the reset. power both down and disconnect everything from both (including coax)
then connect coax back to the modem and power it on. give it several minutes to fully boot.
Then connect a known good ethernet cable from modem to wan port on router.
power the router on, give it several minutes. Attempt setup.
With the Arris CM8200 you can follow the same procedure. just make sure that nothing else is plugged into the modem. Only have the netgear router connected to port 1. leave port 2 empty. It has 2 ports but only 1 port can be used on it with spectrum, cox, xfinity. that other port is only useful if you have wan port aggregation (R6400 doesnt') or if your isp supports multiple public ip address (most isp's dont support this)
Try a 30, 30, 30 reset. While gaving the r6400 powered up hit the reset button for 30 seconds, pull the power thing off while holding the reset butgon still for another 30 seconds, then while holding the reset still plug it to the power again holding the reset still. Then try and see if the internet gets detected. Make sure the cable from the modem goes to the WAN PORT (internet port) and not the other 4 ports.
Factory resetting both the original modem and the router worked! Everything seems to be up and running again. Thank you SO MUCH. I am going to wait until the weekend to attempt to have Comcast activate the new modem again just in case there are any other hiccups.
Again, I'd try the same procedure when you change to the CM8200. Its a pretty solid device but many just don't realize that only 1 device can be connected to it.
