I have good ping and Download/Upload speed, but terrible connection, why is this?

[Mr]

Are you pinging inside or outside, or both?
Pinging your router only tells your internal network connection.
Open a command prompt and Ping ...
Microsoft.com
Google.com
Youtube.com and see what they show .

Your upload speed is terrible compared to the download.
And seeing that you need a certain minimum amount of upload speed in relation to the download especially when connecting to streaming media & game servers, your upload speed is most likely the problem here.

First try unplugging the router for a couple of minutes then plug it in again and try that.

If that doesn't work , go into the routers admin settings & make sure QOS is enabled and set your Upstream (or up-link) to manual.
Whatever your network package speeds are, set them to that speed.
EXAMPLE:
Lets say your upload speeds are suppose to be 10MB? The setting in it are usually in KB's, so set it
Set it to 10,000 kb ( but at your package speed)