From the official 2.5.1 manifest:
: Some users reported issues with multi-WAN port forwarding and VPN stability specific to this version. Download pfSense Community Edition Pfsense 2.5.1 Download Iso
Searching for an older, specific release like (released in April 2021) requires looking beyond the standard download page, as Netgate typically only hosts the most recent stable version to ensure users have the latest security patches. 📥 Where to Download pfSense 2.5.1 From the official 2
Look for: pfSense-CE-2.5.1-RELEASE-amd64.iso.gz Pfsense 2.5.1 Download Iso