Ethernet Connection Not Working on Newer Routers

First time posting here!

This is a strange problem that I am trying to isolate. I would appreciate any ideas about the issue.

I am having issues with making a wired connection on newer routers. My device connects properly to my older router and also is able to connect if I create a bridge to the Ethernet port on my Mac-book.

The problem seems to arise on newer routers. I was first unable to connect to my ISP’s router, so I bought a newer router and have the same problem. Here’s some of the details.

First of all the lights on my Ethernet port do not even flicker with the newer routers. If I connect the Ethernet to the Ethernet port on my Mac-book, it instantly flickers and works.

vEtherISRCallback will not be called on these newer devices, but will immediately be triggered when plugged into the older routers.

My device sends out a DHCP discover, but I am thinking the problem is at the Ethernet level due to this interrupt not being triggered? Could there be a newer protocol on these newer devices that I am not aware of?

Any thoughts would be appreciated, even brainstorming.

  • I think you are correct that it's not a DHCP. Is your PHY on your board setup to auto negotiate the speed between 10/100/1000BaseT and full/half-duplex? Is the router (actually you sound like you're using a Layer 3 switch or similar) set up to handle negotiating a normal or uplink port automatically or are you using a cross-over cable accidentally?

    Also, by "my device", is this some sort of Renesas eval board? What kind and what are you running?


  • Thanks Larry for the response!

    From what I can see I believe that we can do 10/100 for negotiation, but I don't see 1000. I believe Half/Full duplex is supported for both 10/100.

    For routers that did not work I used my ISP's router. This is a Telus Wifi Hub, no real model name unfortunately. Secondly I used an Eero 6+ router.

    It does not look like I am using a cross over cable, and I have tested with multiple different cables.

    I am using a custom board, but the Rareness controller is the RA6M3 A6M3AF3CFC.

    Also please let me know if you need any further explanation from me. I am semi new to this, so will let you know if I am ever not following along.

  • Can you post the configuation of your ethernet and PHY from the graphic setup in the IDE.



  • Hi Larry,

    Are these the photos that you were requesting? See attached images below.

  • Hello,

    Thanks for reaching out Renesas Engineering Community!

    Could you please provide us the part number of the MCU are you using and also are you using a custom pcb board or an evaluation kit from Renesas?

    Thank you!

    Best Regards,


  • Yes. Also, can you say which ethernet trasceiver you are using a post the portion of the schematic from the processor emac to transceiver to the connector and magnetic. If you are not getting a link light on certain switch ports, something is wrong with the port config you're sending over rmii.  You might need to post that code as well.


  • Hello IK, the part number for the MCU is R7FA6M3AF3CFC#AA0. I am using a custom PCB board.

  • Hi Larry,

    This is the is the Ethernet connector data-sheet

    Exact model: ARJM11B1-009-AB-EW2

    Are you looking for me to send the schematic of the custom PCB?

    As per the RMII code. I am currently using the code that has been generated by the Renesas Smart Config. I am on version 4.3. So no custom code there.

  • The ethernet PHY chip you are using is what I was asking - that's what the RMII is connecting to from the MCU.

    Take a look at this explanation. The config does allow a selection of different vendor's PHY chips but you may still need some extra/specific configuration if you're not gettinging link.

    Post the schematic between the MCU, the PHY, the magnetics, and the connector.

    Post the config for the EMAC and the PHY.  Look at the examples in this to see what we mean.

    Read through this app note - it might clear some things up for you. It's a very good doc.

    Also has your HW people if they copied the design from a Renesas Eval board design - that might help also.