Maybe you need to run a router-reset or just a simple edit on the router's page.
for a quick solution...
Depending on the model, usually you should follow some basic steps:
1.
Turn off the router.
2.
a. Check for the reset button;
b. Use a bobby-pin or a matchstick and keep it press
3. Power the router while keeping the reset button pressed (5-10 seconds depending on the manufacturer).
4. All the led's should light up and stay lit; after 5-10 seconds, after releasing the reset you should have a factory reset router.
OS