Slow internet generally happens because of overload on server, when the over the limit people try to access the server which is more than its capacity this makes the server busy and responds slowly all the pending requests are delayed and are processed one after another by the server so sometimes this makes the situation difficult for the users as they are not able to access the data real time they have to go through a queue and have to wait for long times for every request they make to the server.
Weather can also be a major factor in terms of slow Internet if we are using a satellite connection due to cloudy weather it becomes difficult to get signals
There are many other factors as well like DDoS attack which is also called as distributed denial of services attack
How to troubleshoot?
slow internet is to turn off the router from the main switch and turn off the computer and restart after that wait for one or two minutes MC if the Internet speed is back to normal if the speed is not back to normal then you can go to google.com or youtube.com or and check if these sites are working fast or not because most of the time these websites are working 100% correctly and are reliable if these websites are working fast and the website that you are trying to access is not working there may be a chance that your website server is down you can also check other common social media websites like Facebook Instagram WhatsApp if they are working correctly or not