>>435972Different anon here.
If one device works fine and another doesn't, look at the failing device. If multiple devices are failing but one is good, it could be microwave interference (if failing devices are wifi as wifi is microwave radio) ir it could be that someone set QoS rules to stiffle the other devices. Previous room mate perchance?
Download the settings from the router to your computer, there is usually an option to do so in the router interface, just make sure you save the config yext to the desktop so you can find it easily should you need to restore, then Google the default wifi password for the router so you can log back in easily if you don't have an ethernet cable on hand, then do a hardware reset on the router. Methods vary from router to router, but there is usually a recessed button by the power input. Use a paperclip to hold it down until all of the lights on the front of the router flash off and on one or several times.
If it won't get back online or otherwise messes up, you can restore the settings to the router.
Best of luck and don't be afraid to call a pro if you need the help. Paying the fifty or one hundred dollars is oftentimes worth it in the end.