I am trying to get reasonable wifi to a CCTV camera at the side of my house. The BT Hub2 reaches 3 other cameras without any problem. I have now tried 3 Extenders from Amazon. The first was just useless and the second 2 TP-Link products seemed to match the router OK and I had all indicators showing a good connection. However, there was not even 1m extension to the router range. I have been in contact with TP support who were very attentive, but there best suggestion was a cable linked external access point. That is an expensive sledge hammer to crack a nut. The last extender tried (AX1800 RE605X) was installed and had the correct indications on the external wall concerned. Any suggestions or it will be going back to Amazon as well.
Where are you placing the extenders? A common mistake is to place them next to the device you want to serve. In that scenario you are just trying to extend a weak/unusable signal. If you haven't already, initially pair next to the router & then try midway between the router & the problem device.
The Smart Hub 2 is designed to be used with the complete Wi-Fi Discs from BT the Black Discs. I have two of them and have a strong Signal all the way to my Summerhouse the Blink Outdoor Camera system works fine by accessing the nearest disc.
“there best suggestion was a cable linked external access point. “
That is excellent advice. Wired is always the best option especially for camera systems
I set up the extender in the same room as the router and then move it as you suggest. However, the range of network does not seem to be extended. I have been through this process with TP support, but the range never seems to improve outside the house despite the extender being 10 m closer to the external wall than the router. I started with the cheaper end TPs at just over £20, but I am now trying with one at over £50 which is a much larger device with external aerials. The extenders just never seem to penetrate walls or windows like the router does.
Just for a sanity check, you are connecting to the extender's SSID & not to the Hub's? An extender isn't a mesh so will have it's own SSID.
If you have good signal at the internal wall but not on the other side, maybe you have some kind of metallic insulation in between.
You may be able to change the extender's SSID to match the Hub but no idea if that would satisfy the camera software. You'd have to try it & see.
If not then you'll need a mesh system, but again you're in the world of an "expensive sledgehammer. Only cheap solution I can think of would be to buy a black BT mesh disc from Ebay or Facebook Marketplace, as I think that would replicate the Hub's SSID. But you'd need confirmation on that from someone using them & that a disc sourced through unofficial channels would work.
Edit: Looking the the specific extender you were using last, it appears that it can indeed replicate the Hub SSID.
Mains linked wireless hotspots normally work fine, as long as both ends of the link go back to the same common mains consumer unit. They do not have to be on the same ring main.
Most houses only have one domestic single phase mains supply.
Wireless repeaters (extenders) are never a good solution.