Just flashed SP08. Now have the GUI login but can't get in with admin/admin. Have I missed something somewhere?
No, nothing has been changed. The correct, default, credentials are
admin/admin.
Perhaps, with nothing connected to the HG612 (other than the PSU, of course), give it a "long reset". Press the reset button, hold it depressed for 15 - 20 seconds and then release it. Wait a couple of minutes and then power-cycle the device.
Is SP08 still the go to or is there a later version somewhere?
As shown in
red, at the head of the opening post to this thread, the most recent firmware image is
B030SP08.