iPad Air 2 wifi issues

Hi everyone!

So, as you can tell from the title, my iPad has wifi issues and I need some help on how to fix them.

I have been having Wifi issues since sometime around when iOS 9 was released, and the problems have continued ever since.

My iPhone SE has been having Wifi problems recently as well, similar to those of my iPad.

I asked my parents and they both said they have the same Wifi issues as I do (they use an iPad Air 2 with cellular, an iPhone 4 with cellular, and an iPhone 6S+ with cellular).

I don't think it's my router having issues since the Windows devices in the house have barely any trouble with the Wifi. (or if it is, it might be the router being incompatible with the Apple devices on account of the router being from 2013?)

My dad says that for Apple devices to lose connection to the Wifi every once in a while is 'normal'.

Anyone know the reason for this and any fixes? I have tried hitting Renew Lease, soft reset, etc.

Devices: iPad Air 2 (no cellular), iPad Air 2 (cellular), iPhone SE (cellular), iPhone 6S+ (cellular), iPhone 4 (cellular)

Issue: Wifi connection drops occasionally, especially when watching videos (example: YouTube)

TL;DR: All Apple devices in my house have wifi issues, all on latest version of iOS, yet the Windows devices have no wifi issues at all despite being the farthest from the room where the router is. Any fixes besides soft reset and Renew Lease? (Already tried those)