I just installed Fedora 25 and one of the first things I went to do was dnf update, I got the error above.
Is there a known fix to this issue or would I be better off installing a different linux distro?
Freshrpms was an add-on repo which stopped operating about 7 years ago. That's why you're getting that error message. This is not something you'd get from a clean install of a Fedora OS, since Freshrpms is a third-party repository entirely outside of our control. Are you, perhaps, following some guide for enabling additional software? Sounds like that guide is out of date.
(Note also that Fedora 27 is the current release, and I highly suggest starting there. That won't solve this issue, though.)