I want flash regular(non branded) firmware on ZyXEL P-2812HNU-F1 router, which have branded version of firmware (customized for local MSO provider). To do this, I should first replace the U-Boot image on the board. The full procedure is described in Wiki. However, this procedure is for installing OpenWrt on ZyXEL P-2812HNU-FX series. In my case I just want flash the regular unbranded firmware version from the manufacturer's repository, not OpenWrt.
What's not clear: do I need another special U-Boot version, tailored to regular generic (nonbranded) ZyXEL firmware, or I can use U-Boot version created for OpenWrt?