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I use the setup as above ONT > Switch > split to Edgerouter ER-X and T3200M. The T3200M only handles the Optik TV and the ER-X handles my network both wired and an UniFi Lite for wireless. Works perfectly.
Your way would work but then you have to get the Edgerouter to allow OptikTV traffic to the T3200M. By default the Edgerouter would block that traffic (IGMP if I recall correctly) - so you would be left having to modify the default Edgerouter firewall using CLI etc. I did investigate doing just that - there is fairly good information on the Ubiquiti website and in the their Community ... but in the end it was rather complicated for little payoff. It seemed better to in effect just allow Telus to do its thing with the T3200M for OptikTV ... and then if something goes wrong they can't blame you and your Edgerouter :-)