Using own router with MTS fibre internet

I just had MTS fibre internet installed in my home, no TV or phone service. They installed a Lucent Alcatel ONT and a Pace 5168N router. I would like to use my own router. I know that I can enable DMZ Plus mode on the Pace router, but I would prefer to eliminate it completely as many people do in similar situations with Bell, Verizon, etc.

The Pace router is simply configured for DHCP on the WAN port, no PPPoE or anything like that. Plugging my own router into the same port on the ONT does...

Using own router with MTS fibre internet