Download inssider on the computers that aren't connecting/getting low speeds to see what channel you should be on.
http://www.metageek.net/support/downloads/
Call telus and ask for a wireless extender (free, but they charge for running wire to it), (chances are there are quite a few people using telus around you, which is interfering with your signal. when i had the wireless extender installed, it picked up like 7-8 other people using telus).
And lastly check your devices to see which wireless cards they are using, (a/b/g/n/ac) and configure the actiontech as such.
that's what worked for me, (slow download speeds, normal upload speeds), i'm now getting what i pay for.