iSCSI ipxe.pxe/sanboot error 1d704098

[IBIT.ZEE]

I have a Windows 2016 configured as iSCSI Target...

I connect OK to the iSCSI drives from other machines in the LAN
with the Microsoft iSCSI client (iscsicpl.exe)

When I try to connect via ipxe.efi/sanboot it gaves me this error:
"Could not open SAN device: Input/output error (http://ipxe.org/1d704098)"

consulting the suggested URL:
---
Possible sources
This error originated from one of the following locations
within the iPXE source code:
drivers/block/scsi.c (line 494)
---

the ipxe script lines for the iscsi config/invoke are:
---
set initiator-iqn iqn.1991-05.com.microsoft:server1
sanboot iscsi:10.0.0.1:tcp:3260:0:iqn.1991-05.com.microsoft:disk1 ||
---

PS:
* 10.0.0.1 is the NIC I have on server1 for iSCSI service
* as I said... it connects OK with the Windows iSCSI client

I downloaded the last ipxe.efi binary from "http://boot.ipxe.org"
and try other 2 older binaries with the same result...

?does anyone have any ideas where to look??

[IBIT.ZEE]

Well--- as "always"... it is a somewhat stupid thing...

I was assuming that the first-and-only disk I have set in the Server (Target) was LUN0...

and I was using the simple iSCSI URI:

iscsi:server1::::iqn.1991-05.com.microsoft:disk1

as "always"... there are Microsoft things that only Micro$oft '''understand''':
the target disk (the only one in the system) was beeing set as LUN1???

as I can't see this information in the Windows Server Target
only with a diagnostic tool i could find that LUN1 (and not LUN0)
was being set by the iSCSI Server

Sooooo...

iscsi:server1:::1:iqn.1991-05.com.microsoft:disk1

works fine...