
never heard of this website, but i did a test, and its a bit bumpy, no spikes though.
If your directly connected to the modem, and still have anything worse than what im seeing.
Then you need to contact your ISP, and have them check your Coax cable from the back of the modem to the outside of your home/building ect going out to the pole.
Normally recommended to get fresh cable every 6-8 years, if they haven't done it, now would definitely be the time to have that done. ( They may charge a $50 service fee )
If you have any Modems/Routers that say Docsis 3.0 , that is old.
If you have the brand TP_LINK , throw that shit outta the window.
Hope any of this information helps !