We are planning a root cellar for vegetables, potatoes, and so on

That's exactly how we tried it. The two powerline adapters (from tp-link) somehow do not communicate with each other. At first, the connection still worked over half the length of the garden.. (not at all to the basement). Later, the repeater only caused Wi-Fi connection drops. We're running out of ideas.. :(

Did you lay the line to the basement yourselves? Are there any additional protections installed?
In the end, an electrician will probably have to measure.
Since I have never had such distances myself... Have you tried simulating the distance with a cable reel to see if the TP-Links can technically handle it?

How did you perform the test up to half the garden length?

Did you lay the cable to the basement yourself? Are there any additional fuses installed?
In the end, an electrician will probably have to measure it.
Since I never had such distances myself... Did you ever simulate the distance with a cable drum to see if the TP Link devices can technically handle it?

How did you perform the test up to half the length of the garden?

Yes, the cable was laid by ourselves. There are no fuses in between. We simulated it with a cable drum... during that, the TP Link devices "allegedly" connected and WLAN was briefly available... but then the WLAN dropouts started (the LEDs on the TP Link repeater flickered "off" and "on"). At half the length of the garden, there is a shed with a socket on the same circuit. We will first replace the powerline devices and then see how it goes.

Yes, the line is self-installed. There are no protections in between. We simulated with a cable reel... the TP-Link devices "allegedly" connected and WLAN was temporarily available... but then the WLAN dropouts started (the LEDs on the TP-Link repeater flickered "off" and "on"). At half the length of the garden, there is a shed with an outlet on the same circuit. We will first replace the powerline devices and then see how it goes.

Great, maybe they really lack the necessary punch for this distance. Something else – though not so elegant – I once did, two WiFi directional antennas. Worked well except during snowstorms or heavy rain. If nothing helps at all, then probably a 4G/LTE SIM solution with a cloud-based measuring device in the basement with an antenna (you have ventilation anyway). Depending on how complex you want it, you could of course also build it as an IPsec VPN to your home network, so no cloud is needed and everything stays "local".

Thank you very much for your tips and advice.. We've had enough of electronics for today ;) We're going swimming now.. :)

Pharaoh's tomb. :)
I would add a few sphinxes as well.

I just thought the same when I saw that :D

I just thought the same when I saw that :D

I had to bow to the majority decision here.. the men thought it was so fancy. ;) For me, the entrance would have looked simpler.. without masonry steps and preferably a bit with wood.