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I have a board based on an Atmega328 and an ENC28J60 which uses uIP.

When the board is connected to the network via a switch it can acquire an address via DHCP faultlessly. The DISCOVER, OFFER, REQUEST and ACKs come through fine.

When it is then connected to the network via Powerline/Homeplug adaptors, it fails to aquire an address via DHCP. Using Wireshark I can see that the DISCOVER is sent out and an OFFER is made after that nothing happens and the process repeats itself. From some debugging I can tell that the ENC28J60 does not seem to receive the OFFER and hence keeps sending out DISCOVER messages. I've also run a Wireshark downstream of the Powerline adaptors and the OFFER is getting through past the adaptors.

I have tried setting up an alternative DHCP server on the network and the same problem remains. Also, I have connected a laptop to the Powerline adaptors and it can aquire an address via DHCP (this has also been confirmed from a Wireshark capture).

I have played with the QoS settings on the Powerline adaptors without any success and am now not entirely sure how to proceed?

user894893
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    Can you connect another machine and to the powerline adapter and can that obtain an IP? – Dean Apr 14 '13 at 11:41
  • Yes - "Also, I have connected a laptop to the Powerline adaptors and it can aquire an address via DHCP (this has also been confirmed from a Wireshark capture)." – user894893 Apr 14 '13 at 11:48
  • I've seen a question before about an Arduino shield able to send packets onto the network but unable to receive them. I believe it was using the same chipset. http://electronics.stackexchange.com/questions/55424/arduino-dhcp-errornow. – jippie Apr 14 '13 at 11:57
  • @jippie Interesting, but this only happens over Powerline adaptors. When connecting it to a switch it works absolutely fine. – user894893 Apr 14 '13 at 12:00
  • @PeterJ It was worth a try, but unfortunately it didn't make a difference. – user894893 Apr 14 '13 at 12:04
  • Using the same cables as when you connect to the switch? – jippie Apr 14 '13 at 12:05
  • @jippie Yes, I was using the same cable. I've also tried a few other cables just to make sure it isn't that. – user894893 Apr 14 '13 at 12:14
  • Did you capture the packets from the other machine which are successful via Powerline? If you compare them with your failing packets, maybe you find a minor but significant difference. One other thought, the other machine might use DHCPv6. – henning77 Apr 17 '13 at 20:09
  • The next thing I would try is configuring the laptop to force 10 megabit half duplex and seeing what happens. I wonder if the powerline adaptors are buggy in that mode. – Peter Green Oct 24 '15 at 23:11

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