Server not responding issue

I made a server the other day, and everything worked fine. I port forwarded and everyone was able to get on and my server appeared in the main server list. But today when I tried to open my server up, I was able to get on but none of my friends could and it gave them the message that “the server is not responding”. I searched for a way to fix this on google but nothing came up. I checked over my port forwarding and everything seemed fine. Does anybody have a way to fix this please?

Thanks,
Chester


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