Save a WMS layer on your Hard Drive via QGIS?

In QGIS you can use R-Click and Save As... to save the WMS, and any other service, as a raster image.

It saves is at a tiff, and the resolution needs to be set by you. There are other expression and creation options as well.

You can use GrassGis which is installed alongside with Qgis. There is the tool r.in.wms which will do the work.

It is in the background creating a textfile with the GetMap queries and replaces the extent for each tile. So you set it up with the correct region, the size of the tiles you want to have, the imagetype (depending what the wms offers) and thats it. It then sends the Queries automaticly one after the other using wget. After its finished you have to merge the tiles.

The downside is you need roughly 1-2 hours to be able to get along with GrassGis far enough to set the region extent and start the tool (GrassGis is pretty different from other Gi-Systems)