Size of barrel connector of power supply from NAS236?: 5.5 x 2.1 or 5.5 x 2.5 mm?

I got a used NAS236 from the dealer with the wrong power supply.
I want to get a replacement (and have the dealer pay, he has no replacement, is from an office closure). What connector size is it?
5.5mm x 2.1mm or 5.5mm x 2.5mm.
@ Zyxel, I don't want to buy an "original", I know this is standard.
Successfully connected a power supply from another device. Of course I want a new power supply, I need the other power supply for the other device. It is also undersized with 3A.
Such a power supply with 12V 5A may cost $ / € 10.

But I have to know whether 2.1mm or 2.5mm.



#NAS_Apr_2020