Generic:

http://digitalphone.speedtestcustom.com/


AT&T Customers:

http://speedtest.att.com/speedtest/

Spectrum legacy Time Warner Cable:

https://www.spectrum.net/support/internet/spectrum-speed-test/


Comcast Communications (XFINITY):

http://speedtest.xfinity.com/


CenturyLink:

http://www.centurylink.com/home/help/internet/internet-speed-test.html


Verizon:

https://www.verizon.com/speedtest/


Others:

https://www.speedtest.net/


Related Information

https://www.ookla.com/articles/speedtest-experience-ratings  

https://www.speedtest.net/about/knowledge/how-much-speed-you-need  

https://www.highspeedinternet.com/resources/what-is-a-good-download-upload-speed  

https://www.ookla.com/articles/speedtest-experience-ratings  

https://www.t-mobile.com/home-internet/the-signal/speed/got-need-for-faster-internet-speed 

https://kb.netgear.com/29396/What-is-the-difference-between-2-4-GHz-5-GHz-and-6-GHz-wireless-frequencies