3D warehouse says no internet connection

I’m using Sketchup 2018. When I try to import 3D files from the warehouse, a dialogue box now says that 3D warehouse ‘requires an internet connection etc’. Definitely connected to the internet, and occurs on both the laptop and pc, and on different networks. When I access the web version of the 3D warehouse, it offers me options of downloading 2019/2020/2021 versions of the models (which are not compatible of course…), so I am wondering if 2018 is just no longer being supported? I’ll upgrade if I have to but I’ve not received any information saying that this would now be an issue.
Any help appreciated - thank you.

See this regarding the no internet connection thing:

The 3D Warehouse supports the latest three versions so at this point that would be SU2019 and newer. You can still access components that were created in 2018 or earlier but the Warehouse isn’t converting components back to 2018 or earlier versions. You can search the 3D Warehouse through the Components window instead of the 3D Warehouse UI. Or you can go to the 3D Warehouse via your internet browser to get components. Download the Collada file and import the included .dae file into SketchUp.

FWIW, the discontinuation of support for 2018 and earlier was announced on the 3D Warehouse page some weeks or maybe a couple of months before it occurred The change took place last month so they actually waited quite awhile after the release of 2021 to stop the support for 2018 and 2017.