I think MT7621A is a common one. I didn't exactly tear up one yet, but I will. According to chatgpt it has these specs:
CPU: MT7621A
DSL Chipset: MediaTek MT7550
Even if DSL chipset doesn't have it, it still could've been useful for WAN. This thing is dead cheap here. Also MT7621A has hardware NAT am I right?
Could you extract info from OEM boot logs instead of internet fairy tale? 7550 is FE while 7621 is GIGE, your specs make no sense.
Where do you download firmware updates?