How to fix slow-ass inconsistent 5ghz wi-fi from my laptop?

I do know for a fact that when my mom is streaming her Asian shows from literally halfway across the world that the internet will lag a lot. But I noticed even when she stops doing that, my internet from my laptop can randomly sometimes continue to slow down. When the internet gets slow, I can't even watch QHD videos without constant buffering but when it's fast, I can easily watch up to 5K with little problems. Now in the past few days it's gotten so bad that sometimes even FHD videos are sort of lagging on me!

For context, the wi-fi is 5GHZ, I'm using the 2019 model of the Acer Nitro 5, the modem is all the way downstairs in the lounge while I'm upstairs in the bedroom above the garage, and internet speeds are 30-50mbps down and 7-10mbps up at its best but when my mom lags the internet it goes as low as 750kbps-5mbps down and 2-5mbps up! I've tried restarting my browser, restarting Windows itself, disconnecting/reconnecting the wi-fi, turning the modem off/on, but they don't do shit or it's only temporary. I think my laptop might also be a semi-culprit because it's been fucking up this past half year.

Besides not doing more demanding tasks online when my mom is streaming her bandwith hogging shows, what else can I do? I have considered un/reinstalling the network drivers in device manager, but that's probably just a workaround. I will consider reinstalling Windows at a later date though not right now so I don't know. Don't tell me to buy a new computer because aside from a few quirks, my Nitro 5 laptop is working perfectly fine (it also has some battery and cooling issues in the past few months). I think I might consider using ethernet but I don't know if I can just plug in a cable to the wall and expect that to work somehow.

How to fix slow-ass inconsistent 5ghz wi-fi from my laptop?
Post Opinion