Some background: I rent a one story house, built on a concrete slab, walls appear to be timber and gib. Fibre connection is through One NZ. The ONT and router are in a room in one corner of the house, TV with Chromecast with Google TV 4k dongle is in the diagonally opposite corner of the house. WiFi connection when in the lounge is weak (eg 1 out of 3 bars) on all devices (phones, Chromecast, laptops) but strong enough for web browsing and basic stuff. Router (Vodafone supplied Ultra Hub) has both 2.4GHz and 5GHz and is positioned on a shelf at head height. Because we're renting and can't go under the house, all devices are running on WiFi except for my PC which is in the same room as the router.

Problem: Even though the WiFi signal in the lounge is weak, most of the time streaming to the TV is fine using Netflix, Youtube, ThreeNow, TVNZ+, Disney+, Acorn TV and Tubi. However, most evenings around 7:30pm, the streaming changes from running fine to buffering (eg 10 seconds of playing, 5 seconds of buffering, rinse and repeat). Occasionally this can happen at other times of the day (eg Sunday mid-morning). It'll be playing just fine and then *bang* we get constant buffering. When the buffering starts I've switched to other streaming services and they all do the buffering, so I don't think the problem is the service. I've also tried pausing the video to allow the buffer to fill a bit before continuing watching, and this does seem to work for some services but not really for others (I'm not sure what controls the size of the buffer, is it the Chromecast or the app running on the Chromecast? Some of the services seem to have small buffers and stop downloading when their small buffer is full, while others have larger buffers).

Question: Why would this happen? I can understand if the weak WiFi signal causes buffering all the time, but the fact that there are times of the day when it works without buffering kinda suggests to me that the WiFi, weak as it is, is still strong enough to stream. Could my connection speed possibly be affected by others in my neighbourhood? I've tried waiting for the buffering to start and then using my PC (wired to the router) to steam and it streams just fine with no buffering, suggesting that the problem isn't with the streaming services or with One.

I've tried using a WiFi analyzer app on my phone to pick a channel that has the least amount of competition from my neighbours (my immediate neighbours WiFi signal is actually stronger in my lounge than my own WiFi). That may have made a slight bit of improvement, but not enough to fix the problem.

I'm now considering buying a WiFi mesh extender (looking at a NETGEAR AX1800 4-Stream WiFi 6 Mesh Extender EAX15 but am open to other suggestions). I know that One offer a free mesh kit for those having WiFi issues but that's only available if you're on a post-pay mobile plan and I'm on a pre-pay plan that suits me just fine so I'm not looking to switch. I've got a couple of power points that are about halfway between the router and the TV that I can use, one in a hallway and another in the loft.

Anything else I could try before buying the WiFi extender?