Foil is on the insulation boards!
Well you mentioned WiFi extender and I have a FritzBoz! as my home router. You made me remember that my ISP sent me another one - newer but basically the same box. FritzBox support Mesh network and they only work in Mesh between AVM products.
So I tried it. I installed the new box above the ceiling insulation boards - around 15m from the main router with a brickwall and a window in between. Then routed an Ethernet cable to the main switch in my garage.
Result: the ceiling insulation is not enough to stop the repeated WiFi and the box connects to my router at 5Ghz at 500Mbit/s (actual test show 200Mbit actual throughput via Ethernet). I'd say similar results than before with Powerline - but lower and more consistent ping.
And no more interferences. Only downside, the Siglent doesn't like the new WiFi - I understand it's a known issue with the Siglent but it was ok with the Powerline Wifi... RJ45 it is. (tautech, I see you are a Siglent distributor, any help on this?
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So, thanks. Indeed extending WiFi was my second option but I know that extending WiFi can be sketchy so I went for Powerline instead. But since I got this new Fritzbox for free...
Trigger set to the amplitude? Can you elaborate a bit more?
Adam,
Thanks for searching that for me. Do you think that would have helped considering that an isolation transformer didn't? In the end the oscilloscope is always going to be connected to the DUT - which is connected to mains