Im pretty sure the answer is going to be "no"

Question

Im pretty sure the answer is going to be "no"

due to my recent findings on the subject.. but i feel like i need to ask here anyways, just in case any of you guys have good ideas lol.
our client has a very specific problem and he wanted us to find a creative solution, basically using an android phone as a gateway to reach someone's LAN network, and then be able to manage that person's computers, sort of.
so, for that i suppose the network adapter of the android device would need to be in promiscuous mode, right? and this is pratically not possible without root, right? we need it to be just the phone, no extra wifi adapters hanging around.

i know the information im giving is somewhat vague but im not allowed to give more details lol