Main changes between OpenWrt 23.05.4 and OpenWrt 23.05.5
Only the main changes are listed below. See changelog-23.05.5 for the full changelog.

Device support
ath25: fix PHY MII settings
ath79: fix PHY MII settings
ath79: GL-AR750: fix I2C pins
ipq40xx: fix PHY MII settings
ipq40xx: Aruba AP-303H: add PoE passthrough GPIO
ipq40xx: Aruba boards: define config-names, fix compatibility with newer apboot revs
ipq40xx: FritzBox 4040: re-add label MAC address
mediatek: CMCC RAX3000M (emmc): improve bootup stability
mediatek: CMCC RAX3000M: fix lan/wan macaddr
mediatek: JDCloud RE-CP-03: improve PHY reset stability
mediatek: UniFi U6 series: fixup models names
mediatek: Zyxel EX5700: add missing 2.5G PHY LEDs configuration
octeon: ubnt-edgerouter: disable PCIe to improve bootup stability
ramips: fix PHY MII settings
ramips: Sercomm NA502s: use lzma-loader
ramips: TP-Link EAP613: bump EAP610-V3 compat_level
realtek: backport VLAN fix
Various fixes and improvements
mac80211: fix wifi throughput regression
Add kmod-r8101, kmod-r8168, kmod-r8125 and kmod-r8126 driver
hostapd: fix SAE H2E security vulnerability
hostapd: fix anqp_3gpp_cell_net list delimiter
lldpd: many improvements
Core components update
Update Linux from 5.15.162 to 5.15.167
Update mac80211 from 6.1.97-1 to 6.1.110-1
Update openssl from 3.0.14 to 3.0.15
Update mbedtls from 2.28.8 to 2.28.9
Upgrading to 23.05.5
Sysupgrade can be used to upgrade a device from 22.03 to 23.05, and configuration will be preserved in most cases.

:!: Sysupgrade from 21.02 to 23.05 is not officially supported.

ipq40xx EA6350v3, EA8300 and MR8300 require tweak to the U-Boot environment on update from 22.03 to 23.05. Refer to the Device wiki or the instruction on sysupgrade on how to do this change. Config needs to be reset on sysupgrade.
Known issues
lantiq/xrx200 target shows error messages in DSA switch configuration of the integrated GSWIP switch. (see: https://github.com/openwrt/openwrt/pull/13200)
OpenWrt 23.05.5 was signed with the wrong signing keys. The keys from OpenWrt snapshot were used for OpenWrt 23.05.5, OpenWrt 23.05.4, OpenWrt 23.05.3, OpenWrt 23.05.2, OpenWrt 23.05.0 and the release candidates. A later OpenWrt 23.05 service release will use a different key.
Final notes
As always, a big thank you goes to all our active package maintainers, testers, documenters, and supporters.

Have fun!

The OpenWrt Community