Using docker on Win 7 (?)

I have installed docker toolbox on Win7 from here, successfully. If I open the mos web terminal, and try mos build --local, it replies "Docker toolbox found’, does a whole lot of fetching, handling and mounting etc then finnally says:

docker: error during connect: Post https://192.168.99.100:2376/v1.40/containers/create?name=mos_build_2021-09-06T09-59-05-00_531580894: dial tcp 192.168.99.100:2376: connectex: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
See ‘docker run --help’.
Error: exit status 125
/src/cli/build_local.go:697:
/src/cli/build_local.go:684:
/src/cli/build_local.go:449:
/src/cli/build.go:270:
/src/cli/build.go:213:
/src/cli/main.go:198: build failed

any suggestions?