diff --git a/docs/src/hardware/nas.md b/docs/src/hardware/nas.md
index bacc216c04c853376369e31c74f6421456acce01..1689697567ae61e42d05cb3c245a8707a441304e 100644
--- a/docs/src/hardware/nas.md
+++ b/docs/src/hardware/nas.md
@@ -21,6 +21,10 @@ To install the additional parts, you'll have to open up the chassis. Then instal
 
 Further, in order to install TrueNAS, I recommend to remove the pre-installed USB drive from Terramaster installed on the inner side, that contains the Terramaster OS, unplug it and store it, in case you want to send back the device.
 
+## Operating System
+
+While originally the NAS was running TrueNAS Core in it, it was switched to TrueNAS Scale in order to benefit from the automated certificate Management in TrueNAS Scale and run on Let's Encrypt certificates.
+
 ## Power usage
 
 In my tests with no, but just test workload, the average power usage of this NAS was 31W idle using TrueNAS Core, with peaks during usage to up to 39W when having disk activity. During boot up there were some further peaks, I didn't record any further. There is a "natural" boundary of 90w due to the included power supply.