The number one troubleshooting solution to try is the simplest one and often works wonders. It's the one the pro's use. It is the infamous power cycle. Assuming there is power, the power cycle is usually effective and doesn't require the pushing of buttons, which can get confusing and ends up in a service charge.
There are two devices you can power cycle. The modem/POE, which is covered in Grrr. No Internet, or the router, which is covered in this post.
Locate the cord that goes into the power outlet.
Unplug the power cord from outlet.
Wait 15 seconds.
Plug back into power outlet.
Wait for lights on router to come back up.
Check to see if your device can connect.
As always, if this doesn't work, please reach out and a technician will be happy to assist.