We can use the pre-built tools and web terminal to test the internet connection. After login router admin panel, go to "Network > Diagnostics."
Use the "Ping" tool to ping a public DNS server or website to test latency. If returning a "Bad address" error, the internet connection is not working. If ping results have high latency, such as more significant than 300ms, the Internet speed is not fast.
The router's system log includes the records of events and activities on the router, such as various system events, operations, errors, and warnings related to the router's firmware and software.
We can go to "Status > System Log" and check the related error records when some connectivity error happens.
If you need our help debugging the problems, please send the screenshot of the router's home page, paste the above-mentioned system log, and send them to us by email.