What is the name of the domain?
What is the issue you’re encountering
IP Blocked, I was blocked to access APS.org when reading papers and downloading from aps.org with full permission.
May I ask have you tried contacting the Website owner about such case? 
Seems like they’re leveraging the Security features and options from Cloudflare, therefrom some kind of suspicious activity could result in such way that they decided to block your IP address or something else.