Wi-Fi issues may be related to the network or they may be related to the Wi-Fi device joining the network. Usually, if other computers or devices are able to get on the Internet without issues, the problem may be with the device itself. Try resetting your device.
There are many factors that can contribute to slow wireless Internet speeds. For example; a weak or fluctuating Wi-Fi signal can cause problems with your internet speed. If the signal is not strong or unstable, it will struggle to represent the speed you are able to obtain on the device. Also, keep in mind older devices use older wireless technology, which may actually affect the performance of all of your devices on the WiFi network. Older devices may only operate on a 2.4ghz band compared to newer devices which can operate on 5ghz band. Make sure that the network settings of your devices are correct.
The best way to see what speed you are getting is by going to www.speedtest.netor by downloading the app and running a speed test. Before you run the test you will need to close down anything you may have running in the background, as this will effect the test results.
Once you click GO, you should shortly receive a ping, download and upload. These will indicate what your device is receiving from the service.