Exactly like the title says. My downloads are capped at 250 KB/s. No idea why. I did not set any bandwidth limits. My upload is capped at 50KB/s, which I. Anyone can help me?

See if the Auto Limit function is enabled at Bandwidth view. By default it limits incoming bandwidth using 5.0  Incoming/Outgoing ratio, in your situation 5*50=250kB/s incoming limit. You can turn off Auto Limit, or change the ratio by editing (at Bandwidth view) Advanced > Auto Limit Details > Rules > Incoming:Outgoing Throttle Ratio.