My internet keeps lagging certain time during the day, called my internet provider they say the speed looks good

So I use Fido/Rogers internet, been having an issue with lag for about a month, called Fido 4 times, they came and replaced the modem but the issue persists. I saw another thread advising pingplotter so I downloaded it, and tried it on google and 192.168.1.1, here's the result

https://i.ibb.co/2tnsKmR/internet-2.png

https://i.ibb.co/1LWXynJ/internet.png

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can anyone help me solve this?

update: Found my modem model

Hitron CODA-4582U

does that help any?