Can you have a look at the following post, which answers a slow wifi performance question very similar to yours. Have a look at the wifi settings and adjust your settings if necessary to match. Then, as indicated, load inSSIDer and the Lizard Systems wifi scanner to have look at your wifi environment. Hopefully any required changes to the wifi settings and channels will improve your wifi throughput.
https://communityforums.rogers.com/t5/Internet/Rogers-Hitron-CODA-4582-Hardware/m-p/435730#M55170
Please let me know how this turns out. The wifi settings should be generic to any modem or router.