Why won't my Android connect to the internet?

So my Samsung Android with model number SM-T210R and Android version 4.4.2 was going really slow yesterday. After restarting it, it suddenly would not connect to the internet. I tried reconnecting to WiFi, reinserting password, nothing. Checking online, I saw a post saying to try to connect via advanced settings and switch from DHCP to Static and insert IP address. Doing this, I finally got the WiFi signal along with all four bars, but every app tells me that there is no internet connection, despite the fact the device keeps telling me I'm connected.
What can be done next to attempt to restore internet access?

Android has become pretty much entirely useless. Everything needs internet, and mine refuses to acknowledge its connection thereto.
It thinks it is connected, complete with the four bars WiFi, but whenever I try to load an app, nothing happens other than the annoying statement that there is no internet connection.

For instance, when I try to get onto the Wikipedia app, I get the notice:

Cannot connect to the Internet
Retry
Message: "getaddrinfo failed: EAI_NODATA (No address associated with hostname)"