Unable to have the full speed of my internet

Basically, you've got 4 possible causes for this slow-down.

1. Your cable connection.
2. Your router
3. Your wifi connection (either 2.4/5ghz)
4. Your computer
5. Your kids (yes, the true culprits)

To verify your true & real speed; always check-out videotron's own speedtest tool at http://testvitesse.videotron.ca

I'd suggest approaching your problem iteratively with the following steps (from easiest to most-complex) while using the above speedtest service.

1. Ask everyone to turn-off their devices (literally, powered-off!); and only test with your laptop to see if things improve.
2. Try another device to rule-out your laptop (just to have a second opinion).
3. Connect your laptop directly into the router with an ethernet cable; to see if the problem might not be your aging router that just can't handle Videotron's 120mbit of pure speed.
4. Connect your laptop directly into the cable-modem with an ethernet cable (remember to power-cycle the modem first!), to see if you might need to engage a service technician.

Another good read:

https://lifehacker.com/why-is-my-internet-suddenly-so-slow-1525144792

But you can also call videotron's tech-support :smileywink: