Thankfully it’s a quick fix
Those using ASUS routers with ASUS AiProtection have found themselves blocked from the internet due to a bad update on the ASUS servers. You may be wondering how an update on ASUS servers affected the connectivity of remote routers and you would be right. The ASD feature on ASUS routers communicates with TrendMicro to keep abreast of current threats roaming the Internet and will prevent suspicious traffic from affecting your home network. Chances are the bad update managed to mark all traffic as nefarious, hence the loss of connectivity.
The fix is pretty simple for the most part and a good habit to form too; restart the router and everything should be fine. If that doesn’t restore the connection, you can try updating the firmware or doing a hard reset. You will lose all of your configuration settings, but that’s a small price to pay to get your cat videos back. Just press and hold the RESET button on your device for 5-10 seconds and you should be back up and running. If it still doesn’t work, follow the links on Bleeping Computer for steps on how to contact ASUS to have the router reroute packets.