Netgear C6300 - can't access work email Server

Hi!

Currently, I am not able to access my work's email server through my home network. I can access the internet but when I usesites like https://downforeveryoneorjustme.com/, I get the message that the server is down for everyone. However, my colleague who has access to it gets a different message. As a result, I think there's something in my network that is blocking the server.

I've talked to IP but they told me that the issue is with my modem. However, when I've looked at it, I couldn't find any block sites or services. Given this, is there any other way for me to determine if my modem is blocking my work's email server?

Thanks!