Why did you opt to use your personal modem?
If you use the x1 modem, one port of the modem would go to your personal router (assuming you're gonna bridge it),
and one port (port 4) of the modem would go to the security system, on that port I removed their router and placed a switch.
The wireless for your security system goes through the x1 modem.
My speed is 170+ with ease.