Edit - Per spectrum, these routers aren't going to work on their network.  I wish that was the first answer I got.

They have an approved hardware list, and these are not on it.

Okay, so Friday I purchased these and spent a couple hours setting them up.  Always only a red light.

I called the tech support number and after repeatedly getting disconnected I was finally able to get to a person.  His accent was very thick and I couldn't understand a lot of what he was saying, but eventually I reset one of the devices and replaced the cable from the modem with a known good one, and rebooted the modem a few times, and it finally got a green light.

He said to hook up the other 2 required a special set of instructions that he had to email to me, but he couldn't understand me well enough to spell the email address and eventually the call died.

So anyway I went back to the website and tried a live chat, which said there is no special instructions, just turn them on and they'll connect automatically.  So one of them only ever turned red, but the other one worked.

But all weekend long everybody had to keep logging back in to the wifi every couple of hours, but every device including our printer.  I have several raspberry pis, but they will only connect to the wifi but then they never connect to internet or any other devices. Pinging the deco works, but any other ip addresses just time out. Weird, right?

So I tried running something called "network optimizer" on the deco app, but it just gave a spinning circle for over an hour so I just gave up.

Yesterday, the main computer hardwired to the port on the deco had no internet and none of the wifi devices had internet. All the units were red and I tired for a few hours and nothing would work.

So then we called spectrum and they sent a signal to reboot the modem.  Didn't make any difference.  So then they sent out a service tech who said the modem is fine and didn't know what was wrong with the deco or a bad wire.  I told him it was strange that every wire we have suddenly went bad.  So he got a new modem and hooked it up, and then got out a spectrum router and hooked it up, and everything started working right.

But after he left, I tried hooking up the deco to the new modem directly.  Red light.  Then I put spectrum's router back in the modem, and plugged the deco into a port on the spectrum router, and the deco works just fine.

But if I plug it into the modem directly, it only ever gives a red light.

So I think I messed up by not getting the instructions to hook up the 2 other units, and definitely have screwed up something major in setting these things up.  Could someone tell me if there's a way to factory reset these or something? Because the spectrum router has terrible range, and costs an extra $10 per month which is stupid.