Recently I replaced a defect Desktop switch with a cisco SG-200-8 switch. After I replaced the old switch everything seemed to work fine. Now the employees have trouble using the scanner through TWAIN. After some hours I figured out that using an unmanaged switch the scanning process works fine.

I then scanned some pages and captured the network traffic. There are no malformed frames so I don't see any reason why the switch should drop the frames. Can somebody make sense out of this?

// After many checks I now can specify the problem further. The SYN Packet that is send from the client to the printer is dropped by the switch. Anyway Etherlike does not display any dropped frames. The Packet looks like this:

enter image description here

// As I wasn't able to make any sense from this behavior I think this might be a bug in the firmware. In the release of one firmware update a similar bug is patched that is related to printing. This is not exactly my problem but it aims broadly in the right direction. I will report back if this fixed it.

// After two firmware updates the problem is solved.

  • What do the switch interfaces say about errors?
    – Ron Maupin
    Oct 12, 2016 at 13:33
  • Sadly the don't say anything
    – davidb
    Oct 12, 2016 at 13:34
  • Edit your question to include the output on the switch interface.
    – Ron Maupin
    Oct 12, 2016 at 13:35
  • You mean the packet capture? Or the logged information?
    – davidb
    Oct 12, 2016 at 13:40
  • No. In the switch, you can show the interface. It will give you all the statistics, including errors it sees.
    – Ron Maupin
    Oct 12, 2016 at 13:42

1 Answer 1


The Problem could be solved by doing a firmware update. After the update the scanning process works fine now.

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