Possibly compromised router?

I had a an incident last year where I noticed that my internet connection was not functioning as it used to. The connection was extremely slow particularly when watching video streams. At that time I noticed that the router I was using had a critical vulnerability https://www.spiceworks.com/it-security/network-security/news/authentication-bypass-vulnerability-impacts-multiple-asus-router-models/ and after installing the updated firmware the problems vanished in one go. It should also be mentioned that i disabled WPS and UPnP, did a hardware modem reset when the firmware was finally installed a

Question by jimbrr on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.