ssh and scp get stuck after some amount of data

Hi,

I'm using https://people.debian.org/~sthibault/hurd-i386/debian-hurd-20170115.img.gz
in a virtual machine (virtualbox - very robust with a number of other guest OSes).

Now I need to transfer a 2 GB tree to the host machine (declared as virtual
Ethernet card for the guest).

First attempt:
# tar cf - directory | ssh [email protected] tar xf -
It hangs after transferring 1.6 GB. I.e. no more data arrives within 15 minutes.

Rebooted.

Second attempt:
# tar cfJ tgz directory
# scp tgz [email protected]:tgz
[email protected]'s password:
tgz                                          21%   74 MB   0.0KB/s - stalled -
It hangs after transferring 74 MB. I.e. no more data arrives within 30 minutes.

What's the workaround to get Ethernet connections, ssh in this case, work
reliably?

Bruno