If your ISP is advertising 50 mbps, you should get at least that speed in today's arena. Back when we were using dial up and older cable systems, speeds were not a guarantee but that was back in the late 1990's and early 2000 years. Now, with newer cable/fiber networks, fiber only and better technology in modems, channel bonding and other improvements, most ISP's should be able to provide the speeds the user subscribe to.
You need to post your test results and inform us which ISP you have. Also, it makes a difference if you are testing your speed with a cell phone, laptop or desktop computer. Not all laptops and cell phones can reach the maximum connection speed like a desktop computer will. If you only get 20% of your advertised speed, you have an issue with your ISP and/or equipment. The best solution for remedy is to get the ISP technician out to your location as they are the ones who get things fixed and cut through all the scripts the 800 # folks are told to use depending on what words you use when asking for support. Sometimes, you have to make up something to tell them to get the technician out there otherwise you will get no place. Use some logic if going with that idea such as, "I see a chewed cable/wire going to the house" or similar but as long as you suggest something to them that is on their side of the modem or they will tell you it's your problem. Sometimes it is your problem so find someone if you don't have the know how to check your connections. BTW, when testing you must always use a wired connection to be fair to the results. Wireless is not consistent and not a great tool for testing.