To know if your internet router has been hacked you can look in the admin panel of your router for any unauthorized devices or even look for any DNS setting changes, slow internet or altered admin passwords.
Key indicators and signs that your internet router could've been hacked are browser redirects, unwanted popup ads, your ISP alerting you to malicious traffic, login failure to your internet router, unusual web traffic, security alerts, modified settings and even DNS redirection.
Changes to your internet router that you didn't make like altered DNS settings or enabled remote access or password changes are signs that your internet router may have been hacked.
Or if you get any fraudulent antivirus messages or ransom demands, or you have any security alerts like your web browser warning you of security certificates, or your internet service provider or ISP warns you of any suspicious activity your internet router could be hacked.
If you notice that you have any unusual web traffic like constant, high volume internet activity, even when all your own devices are idle, it can indicate a hacked router and bot activity.
Or if you're redirected to fake or malicious websites when you try to visit the legitimate websites or your internet routers administrator username or password no longer works or you notice any unknown connected devices to your internet router that appear in your internet router's connected device list or DHCP client list.
These are signs that your internet router could've been hacked or compromised.
If your internet router is compromised you can do a factory reset or even get a new internet router and update your password and login information.
The factory reset on the internet router will vary depending on the internet router.
However most internet routers can be factory reset by pressing the physical reset button on the router for 10 to 30 seconds to erase any malicious configurations.
Some internet routers have a slot where you stick a pin inside to factory reset them.