Asked — Edited

One Board Connects To Wifi But Won'T Get An Ip Address

Hello everybody!

Just checking if I may be able to fix this issue otherwise than by changing the main board to my main robot.

This robot has 2 V4 boards (+ 1 V3 that serves only to put everything on standby by controlling a simple relay).

One of the 2 V4 boards will simply not be able to get a stable IP address. Since I use 2 DHCP routers which serve onto the same subnet (but different range of addresses) in order to handle all my devices (40...), I first thought there was some mess with my network configuration so, before I left to Europe for 2 weeks, on Monday I tried pretty much everything, as far as connecting the board to a lone router, totally separated from my network. I reset the board's settings several times, AP mode will work, although not very stable, ARC would lose connection fast and I'd have to power cycle the board each time. This is actually what the first symptoms back when client mode would work : it would disconnect and require power cycling to reconnect, until it would not get any IP at all, although I hear the successful connection audio message, each time.

Let me know if this has happened to any of you and if you found out what caused it. The only thing I didn't try is disconnecting all wires because last time I did that it took me far too long to reconnect everything so this would be a last resort solution, and I'd probably change the board.

It is really weird: successful connection in client mode to the router, but no IP and the router, would actually see its mac address without being able to assign an IP (which can be seen in the mac filter list).

Best regards, Elf├Ęge.


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Elfege, I had a similar problem, I would get a successful connection tone, then disconnect. I traced it down to my project initializing parts of the robot that I had not yet completed and attached (JD's Head). Try connecting the EZB with a bare bones project. Could be a loose camera cable or other I2C device on that EZB.

Hope this helps. RichardZ


You can't have two dhcp servers on the same network. A "subnet" is a reference to an IP address netmask, which is a higher layer in the OSI model than the dhcp request.

You can only have one dhcp server per physical network.

Also - since you're a pretty experienced power user, have you considered using @ptp's firmware with more advanced network options?


DJ, I hate to disagree with you but, if configured properly Split scope DHCP works fine.

Microsoft TechNet Article: Split-scope configuration (Widely known as 80/20 Configurations) is typically considered as high-availability deployment scenario for the DHCP Server. It involves configuring scopes with the same subnet address and subnet mask and configuration on two distinct DHCP Servers. The two scopes have complementary exclusion ranges and therefore will not serve the same address to different clients.

The ratio of address ranges across the servers is denoted as Primary Server to lease 80 percent of the addresses in the scope and the secondary server to lease out 20 percent of the addresses in the scope. Splitting a scope between servers in this way, which is commonly referred to as the 80/20 rule, often relies on the proximity of the DHCP servers to the clients it serves. To avoid address range exhaustion on the secondary (20% address range) server, it can be configured to send out the DHCP OFFER with a small delay as well.


Correct - split scope is not the same as two separate dhcp servers operating with default dhcp behavior. This is because the Mac addresses are preconfigured AND the dhcp servers are aware of each other's presence to identify who's responsible for what MAC address (whether from a pool or static), if they are on separate servers.

By default, a dhcp server (specifically a dumb one on a router, which hands out addresses from a pool by default and that function cannot be disabled) has no reference to another server and will hand out addresses when requested - having no idea of any other competing servers.

I would recommend reading further on:

  1. how dhcp works
  2. the OSI model
  3. software configuration settings of dhcp servers

So, in short and to be more specific to the additional information: you cannot have more than one dhcp server that has not been configured for awareness of other dhcp servers, such as presented by rz and/or other dhcp server functions not specified in this disclaimer.

My statement still stands and may be applicable to the OP. If the dhcp servers in question do not have a feature, similar to what rz has mentioned, then you cannot have more than one dhcp server.

The absolutely only time you can ever ever ever ever ever ever (times infinity) have more than one dhcp server is when the server software supports a feature similar to what was described by rz. At that time, the only ONE of the multiple dhcp servers is handing out addresses from a pool AND has communication with other dhcp servers to know when it should hand out from a pool given that the other servers don't own the rights to assign the client address themselves.

Unless the OP has specifically configured more than one DHCP server with their specific settings to allow a multi-scope style, you cannot have more than one DHCP server.


Wow! Thanks a lot! I've remotely changed the subnet of one routers already and I'll seek to flash the EZB upon my return from France. I didn't want to go it, too too too too many layers of wires to take it out from and got lazy on that one!

Oh I purchased a quite long extension for the camera I guess I should provide it with Its own DC... Right?

Thank you!



The ez-robot camera won't need separate power, even with the extension. It will power fine even with a super long extension. I think the longest jeremie tested was like 12 feet! :)

enjoy France! Must be nice to travel to fun places like that - i travel soooooo much but it's between Calgary and San Francisco only


Just finished spending thre days roaming in Paris, alone and making friends and seeing old ones too. Just magical! But my bank account told me it's about time that I go to my family in Normandy!

Went to SF last fall for robotics training! That was awesome! I'd love to have studied and work in the field! One day maybe I'll stop teaching philosophy and will go back to college! Kind of a dream I'm slowly feeding. :)even though I'm already super lucky to do exactly what I love to do.


Sounds wonderful:D Have a great rest of your trip!


ok, all probs solved thanks to firmware flash. Thanks a lot everybody!



Are you using the custom firmware ?

I'm located in New Jersey, sometimes i commute to NYC, if anyone needs help flashing ping me here.


Hi Ptp! Ans thanks so much for this firmware. I'm using the one you posted in a thread to which I had been redirected by Dj.

Do you have iMessage? If so text me to my email address which is my first name at my first name dot come (elfege is my real first name)

And if not just email me and I'll send u my phone number so we can chat over a drink some day. You may also find me on fb