Not very scientific but you can try something that is unlikely to be whitelisted. Eg. http://134.209.196.181:8080 This is an instance of https://github.com/e7d/speedtest running on Digital Ocean in Amsterdam.
38.69 Mbps Download
154.43 Mbps Upload
While from speedtest.net (to a local server) I get 178.34 Mbps Download
192.23 Mbps Upload
I'd chalk it up to distance/noise except that the download speeds are way more similar than the upload speeds.