There are no "best settings." Your best option is to start with a base and adjust as necessary. Test, test, and test again. The auto-config wizard generally offers a decent baseline to start with. Other than that, different services have different bandwidth caps, and a Speedtest isn't a good measure of connection stability.
Try the auto-config. Work from there. If you have any specific problems or questions after that, we can give more specific advice if we can see a log file.