A patch-level release mainly brings many security fixes, improvements, and updates. You are welcome to check out the Release Notes for the detailed change log.
A few highlighted points from the change log:
- For the ICR-4400 product family, the PoE can be enabled/disabled individually for each of the four ETH0 ports.
- Fixed RTC update when the NTP service did not update the RTC clock.
- The license listing in the router's GUI was updated and enhanced.
- Several miscellaneous bug fixes have been applied.
- BusyBox, tc, totd, curl, OpenSSL software have been updated from version 1.34.1 to version 1.36.0 to fix severity vulnerabilities.
- IPv6 DAD Configuration change.
- Resolved the GRE keepalivemechanism for GRE keepalive packets generated by a CISCO device.
- Many vulnerabilities reported in the National Vulnerability Database have been resolved.
Firmware download for all models available here.
Look into the Firmware Distribution Overview document for details about the distributed firmware versions per particular router.