I have tried OpenWrt on various platforms, RPI4 and x86 on Protectli Vault FW4. For some odd reason both of the Protectli units have failed in less than 6 months. This is not very encouraging. It is also an expensive mistake.
I would have chosen Rpi4, but as we all know it is "unobtainium" at a reasonable price. I tracked down the actual motherboard that is used in the Protecli, but there seems to be little help that can be obtained from the Minisys website in China.
Can anybody suggest a fanless x86 solution that will not fail in such a short period? If anybody wants to know, I have Odroids that have been on 24/7 for years on end. No hardware failure from them at all!