I've experienced the same issue with my brothers recent installation of Shaw 300 installation. The Black Cisco wifi modem is just plain bad at wifi on either the 2.4 or 5Ghz channels using Wifi which it tops out at 35Mbps on several wifi connected devices implementing both the 2.4 and 5Ghz. The wired portion serves up speeds of max 150Mbps which is not what the cost of connection speed is rated but is better. The thing about all the interference etc doesn't sit well because at the same time we have Teksavvy still active and it's going through a D-Link Router that serves up exactly the speed that we're paying for and it's consistent from one end of the house to the other.
Myself I'm on Vianets Fibre 30 package at my cabin and my TPLink router using Wifi connection speed tests on my wifi devices top out at 30Mbps same as wired. At my farm house I have Bell's Wireless Home Hub with built in wifi and another router setup in repeater mode and even connecting through the repeater on both the 2.4 and 5Ghz channels sends speeds topping out the same as wired throughout my farm.
Could it be a ploy in software settings that Shaw implemented so that they won't have people that don't really know what to do and will just call and complain when they see their network cripple while 3 wifi TV's in a person's house are streaming 4k content and little Johhny is downstairs playing Fortnite on the PS4 all wirelessly so they cap the wifi bands not to tax the bandwidth...sort of like bandwidth shaping? This is likely a good theory that I think is happening to avoid the headaches of people switching providers etc.
