CM1100 not connecting to router

For your router, are you talking the RAX80 that you reference in the signature line?

When you activated the modem and it connected to the pc, did you follow the procedure for changing devices? the modem only gets a single public IP address from your provider. it does have 2 ethernet ports but it can only be used for a single device*. 

You can also setup the RAX80 without internet to get it fully updated. Get the latest firmware on it and then factory reset it. The firmware changes were quite significant since release and this can help with setup.

Once the router is fully updated and reset and the cm110 is back activated from your isp, try this:

power off both devices, don't connect anything to either device.

power up the cm1100.  Give it a few minutes to fully boot and connect.

connect port 1 from cm1100 to RAX wan port

Power up the RAX. Give it a few minutes to fully boot.

Then try setup. Don't setup port aggregation at this time. Some of the RAX devices have had issues with wan port aggregation. 

Don't plug anything else into port 2 of the cm1100. I'd give it a bit for the firmware between the cm1100 and RAX to solidify before using wan port aggregation. For some its worked fine, others have had nothing but issues. 

*unless your isp allows more than 1 public ip address. most don't. I know xfinity doesn't for their consumer lines as I have xifnity.