A failure/reboot at that point, which is just before the wifi typically performs a high power operation, almost always means a power problem.
Note that sufficient power is not only about the regulator, filter capacitors, and wiring downstream of it but also about whatever is feeding the regulator, and especially how that responds to the sudden near-doubling of load when the wifi does certain things.
I have a "2 amp" supply here which worked fine for other embedded wifi systems, but seems incapable of reliably running MT7688 boards. I have others rated less than that which work fine.
It really matters more how something actually behaves, especially in its time-domain response to a pulse load, than what it says on a space-constrained label.