Security System Troubleshooting

At our home we have a Xfinity Home Security system with door sensors, this is all controlled by the touchscreen which is ~8 years old.  We recently replaced our non-comcast modem and routers to more current models and in doing so I unplugged a small Comcast router that was connected to our old modem.  As of doing this I am unable to connect the touchscreen to the internet.  I am looking for some assistance and if I need to upgrade the touchscreen or get a new comcast router?  Any assistance would be appreciated.