Why I can't get access to mendeley website? Or mendeley desktop?

Based on the provided information, several common causes can prevent access to a specific site like mendeley.com in Microsoft Edge on Windows 10, even when other sites work:

1. The site or its CDN temporarily blocks the IP address because of unusual or high connection volume. Similar behavior is documented for Microsoft sites hosted on Akamai CDN, where repeated connections from the same origin can trigger an automatic temporary block. In that case, access usually starts working again after some time once traffic from that IP drops below the protection thresholds.
2. Local security or filtering software (for example, antivirus, web protection, or parental/web filters) can block specific domains while allowing others. A similar issue was resolved when a user found that switches in their security product (Norton) were turned off and re‑enabled them.
3. Browser/network configuration issues can affect only some HTTPS sites. For example, in Microsoft Edge, enabling certain advanced TLS features (like “1.3 Post‑Quantum Key Agreement”) caused some sites not to load until that flag was disabled.

Actionable checks:

1. Wait and retry
   • If the site is being temporarily blocked upstream (similar to Akamai protections), it may start working again after some time without any local changes.
2. Test in privacy mode and another browser
   • Open Edge InPrivate and try mendeley.com.
   • If possible, test in another browser on the same machine. If it works elsewhere, the issue is likely Edge‑specific (cache, flags, or extensions).
3. Clear Edge cache and cookies
   • Clearing cache is a standard step when a specific site fails while others work, and is recommended for similar 403/website issues.
4. Check security/AV or web‑filtering software
   • Open any installed security suite (for example, Norton or similar) and review web protection / firewall / safe browsing settings.
   • Ensure that mendeley.com is not blocked or categorized as unsafe.
   • A comparable issue was fixed by adjusting switches in a security product’s settings.
5. Check advanced Edge flags (if previously changed)
   • In Edge, go to edge:flags and search for TLS‑related experimental features.
   • If “1.3 Post‑Quantum Key Agreement” (or similar TLS experiments) was enabled, set it back to Default/Disabled and restart Edge. A similar change resolved widespread site‑loading issues for another user.

If none of these steps help and only this single site fails across all browsers and devices on the same network, the problem is likely on the site/CDN side or with upstream filtering, and may resolve only when that is corrected.

References:

• Error message when you visit a Microsoft website that is hosted on Akamai CDN: Access Denied
• "403 Forbidden" error on OneDrive or SharePoint
• protocol unsupported - Microsoft Q&A
• My edge is blocking literally almost all sites or address I want to visit. - Microsoft Q&A