Hello guys, I'm new here so please don't mind my stupid questions since I just bought Nanopi R4S weeks ago and I'm trying to learn new things but sometimes I can't just find the answer easily online.
New firmware is available which is 23.05.3, I'm still on 23.05.0 and I'm wondering how to upgrade correctly, there are two files for this firmware, one is Sysupgrade (EXT4) the other Sysupgrade (SQUASHFS), which one to use to upgrade using System > Flash Firmware? And is it fine to upgrade from 23.05.0 directly to 23.05.3 and skip everything in the middle? (such as 23.05.2)
The easy way is to install auc (opkg update ; opkg install auc) and let it do the work for you. Both auc and LuCI Attended Sysupgrade have internal logic to detect the current file system format and select the proper installer to match (in addition to keeping around all your user-installed packages).
Alternatively, you can download my package scanner script (see The OpenWrt Firmware Selector - #621 by efahl) and it can tell you all about your current installation, to help you do things manually if you so wish.
Thank you for your help, I installed auc from System > Software, then what to do next? I can't find anything related on the webpage and even in updates tab inside System > Software
auc is the command line upgrade tool (as opposed to the LuCI Attended Sysupgrade web interface). For auc, you need to ssh into your router and run it from the CLI. Both auc and LuCI Attended Sysupgrade are described here: https://openwrt.org/docs/guide-user/installation/attended.sysupgrade
Along with the excellent guidance from @efahl, I highly recommend getting into the habit of backing up your configuration to your PC or anyplace other than the router before any significant change such as an upgrade.
Also, since the R4S uses a sd card, it can be handy to get info with Efahl's script and install the new version with all the updated versions of packages that you added to the current version a new different card. That way you can quickly revert back to the previous known good setup if needed by powering off, swapping cards and powering the R4S back on. Alternate the cards in an A/B rotation.