I'm re-using a wifi router as a switch for my network, but it seems I have severe problems getting the IP address from the DHCP server.

This is the topology: I have a netgear router connecting to my ADSL serving many clients via ethernet and wifi,with a working dhcp server. One of the ports is connected to another digicom router, which is set as a bridge, with dhcp server disabled and wifi AP enabled.

When I connect via ethernet or wifi to my netgear router, I have no problem. When I connect to the digicom switch (which is really a router) via ethernet, it seems to work properly. If I connect to the digicom switch via wifi with a static IP address, I have no problem. If, instead, I connect via wifi to the digicom switch using DHCP, Android, Linux and Mac OS have severe problems trying to get the IP address assigned. I see from the logs that the netgear router receives the request and assigns an address, but the client receives nothing. If I try many times, it seems every OS succeeds, but it may require several attempts and reboots of the digicom switch. After the address is received, everything works properly.

Any idea why it seems the address is not received via wifi from the digicom switch?

This is a scheme of the topology. Everything works properly except those Andorid, Linux and Mac OS clients when connecting to the digicom device via wifi link. Those are DHCP clients. Mac OS is assigned a fixed address in the DHCP server. There are other clients trying to connect here and there, but those are the ones failing.

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  • Can you add a simple diagram of how you have the devices physically connected with assigned IP numbers please? – Tim_Stewart May 27 '18 at 15:04
  • I added a scheme as requested. The upper part has always been working properly and can probably be ignored. The relevant part is the one related to the "new" digicom device where DHCP clients seem not to be able to get an address very frequently. Any reason why the DHCP response should not be able to reach those clients via the wifi link? – Luca Carlon May 27 '18 at 15:44
  • What's the model number of the digicom router acting as a switch? And is this Ethernet plugged in via wan port or lan port? Plug it in via lan if it isnt already. – Tim_Stewart May 27 '18 at 23:29
  • This is a digicom wavegate 54rc. Nothing is plugged into the wan port, only lan ports are used. – Luca Carlon May 28 '18 at 5:28

It seems the problem is solved by preventing devices from connecting to the wifi network of the netgear router immediately before connecting to the wifi of the digicom router. Getting an address from a wifi and the quickly disconnecting from it and requesting another address for the same MAC from another wifi network seems to somehow confuse the DHCP server in the netgear router.

I removed the old wifi connection from my Android, Mac OS and Linux devices and the connection now is very quick. No more issues.

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