M9Plus no longer giving wired DHCP leases
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For around 6 months, I had the following setup working flawlessly:
Modem/Router->managed switch->DecoM9+wired clients
The modem/router is provided by my ISP and DHCP cannot be disabled unfortunately, neither can it be configured to work solely as a bridge.
I want to use the DecoM9 as "master" DHCP server, because the ISP's Modem/Router does not provide address reservation compared to the DecoM9
Summary:
- ISP Modem/Router has 192.168.0.1 and sends out DHCP leases in the 192.168.0.100 and up range
- Deco M9 has 192.168.68.1 and sends out DHCP leases in the 192.168.68.100 and up range
To make sure the wired clients don't get IP addresses from the modem/router, I've split the network up in VLAN's:
VLAN1: port 1 to 5 (port 1: modem/router, port 5 Deco M9)
VLAN2: port 5 to 16 (so Deco M9 is member of both VLAN's)
This way, the wired clients can't "see" the modem/router and get a DHCP address from the Deco M9.
This has worked perfect for wired and wireless clients since february.
Deco M9 got it's WAN IP address from the modem/router (192.168.0.205) and sent out DHCP leases on ports 6 to 16 of the switch and on its wireless network.
Last week, during our holiday, everything just stopped working.
I've reset the switch and the Deco M9 but the Deco does not respond to DHCP lease requests on the wired network. I've disabled VLAN's and disconnected the Modem/router (so keeping only an island of Deco M9 and its wired & wireless clients) but no DHCP leases on wired LAN)
I've dived into it with Wireshark and see clients on VLAN2 sending out DHCP lease requests, but DecoM9 does not respond.
Moreover, when I configure a wired client with a fixed IP (eg 192.168.68.5), it cannot connect to the wired clients on the DecoM9 wireless network (they do get DHCP leases in the 192.168.68.100 and up range)
So to document things a bit further, I set up port mirroring on the Deco M9 wired connection.
Mirroring was forwarded to my laptop that is connected by wire to the same switch. The PC is sending out the DHCP requests, that is why all captured packets appear twice off course.
In the following example, the modem/router by my ISP is disconnected, so only 1 DHCP provider is present on the network. No VLAN's active.
You clearly see the DHCP Discover requests arriving at the Deco M9 but no response. The client tries multiple times without succes/response from Deco M9. On Deco wireless network, no issue.
In a following test, I enabled the ISP's modem/router, who has also DHCP function just to crosscheck. You can see that this works without any issue. So the question remains why Deco M9 master no longer provides DHCP on wired network.
On top of this, I did an additional test. I reconfigured the 2nd DecoM9 and upgraded both to the latest firmware. Both Deco's are connected to each other on the same network switch, but the additional Deco is reporting a wireless backhaul instead of a wired one. Physical connection is working off course. So it seems the main Deco is ignoring all wired packets, even from its Deco "brother", but is still using the wired connection to connect to the internet.