This release fixes a few problems we found in the release 4.1
- upgrading from v4.0 was not actually preserving the MAC address
- upgrading from v4.0 without a management USB connection was going
to stop without completing
- one of the “trivial” changes in our PTP daemon was wrong and
resulted in constant offsets in the synchronization

We released new binaries and a new user manual, describing the
procedure to upgrade a v4.0 switch without an USB cable while
still preserving the MAC address. The procedure to upgrade
with the USB cable is unchanged but the problem with preserving
the MAC address is now fixed.

We (and especially me) apologize for the problem.