SDN DHCP not working

[TechTronic]

Hello All,

I have a fresh install of 8.4.1 in a datacenter, single ethernet port with a public IP. I'm trying to configure SDN to provide an internal subnet for VMs with DHCP and DNS that allows outside access to the Internet. I followed the guide here: https://pve.proxmox.com/wiki/Setup_Simple_Zone_With_SNAT_and_DHCP and also here: https://cyanlabs.net/tutorials/inst...th-1-ip-using-sdn-and-without-kvm-using-qemu/ (which is pretty much the same guide, reformatted). After setting up the Simple zone, a VNet, a Subnet, and IPAM, VMs are not able to obtain an address via DHCP. I even disabled the firewall at all levels to rule that out, no change.

Any help would be greatly appreciated. Thanks in advance.

 

[hd--]

Did you disable the dnsmasq service systemctl disable --now dnsmasq?
And did you also configure a DHCP range in the subnet?
What is the output of the following command?

systemctl status dnsmasq@<put_in_your_zone_name>.service

 

[TechTronic]

Thanks for the reply. I ended up abandoning the SDN config, and decided to install an OPNsense VM instead.

 

[alpot]

This link https://pve.proxmox.com/wiki/Setup_Simple_Zone_With_SNAT_and_DHCP tells you to install dnsmasq, but then it also says to disable the service. Why?

 

[hd--]

This link https://pve.proxmox.com/wiki/Setup_Simple_Zone_With_SNAT_and_DHCP tells you to install dnsmasq, but then it also says to disable the service. Why?

That is because we enable the dnsmasq systemd template unit per zone and if you do not disable the default systemd service they might disturb each other.

 

[Carontes]

Hello, I'm sorry if I write here after a long time from the last message of this thread but I have the same problem. I've set the SDN and gave it a DHCP range and enabled DHCP, but when I create a LXC or VM giving it the SDN zone name bridge with DHCP enabled I receive no IP, but if I assign a static IP from the DHCP range it receives the IP and everything is fine. I don't understant what I'm doing wrong. Proxmox 8.4.16.

systemctl status dnsmasq@myNET.service
● dnsmasq@myNET.service - dnsmasq (myNET) - A lightweight DHCP and caching DNS server
     Loaded: loaded (/lib/systemd/system/dnsmasq@.service; disabled; preset: enabled)
    Drop-In: /usr/lib/systemd/system/dnsmasq@.service.d
             └─00-dnsmasq-after-networking.conf
     Active: active (running) since Mon 2026-01-12 14:54:43 CET; 5min ago
    Process: 95480 ExecStartPre=/usr/share/dnsmasq/systemd-helper checkconfig myNET (code=exited, status=0/SUCCESS)
    Process: 95485 ExecStart=/usr/share/dnsmasq/systemd-helper exec myNET (code=exited, status=0/SUCCESS)
    Process: 95491 ExecStartPost=/usr/share/dnsmasq/systemd-helper start-resolvconf myNET (code=exited, status=0/SUCCESS)
   Main PID: 95490 (dnsmasq)
      Tasks: 1 (limit: 76362)
     Memory: 748.0K
        CPU: 25ms
     CGroup: /system.slice/system-dnsmasq.slice/dnsmasq@myNET.service
             └─95490 /usr/sbin/dnsmasq -x /run/dnsmasq/dnsmasq.myNET.pid -u dnsmasq --local-service --trust-anchor=.,20326,8,2,E06D>

Jan 12 14:54:43 proxmox systemd[1]: Starting dnsmasq@myNET.service - dnsmasq (myNET) - A lightweight DHCP and caching DNS server...
Jan 12 14:54:43 proxmox dnsmasq[95490]: started, version 2.90 cachesize 150
Jan 12 14:54:43 proxmox dnsmasq[95490]: DNS service limited to local subnets
Jan 12 14:54:43 proxmox dnsmasq[95490]: compile time options: IPv6 GNU-getopt DBus no-UBus i18n IDN2 DHCP DHCPv6 no-Lua TFTP conntr>
Jan 12 14:54:43 proxmox dnsmasq[95490]: reading /etc/resolv.conf
Jan 12 14:54:43 proxmox dnsmasq[95490]: using nameserver 192.168.10.16#53
Jan 12 14:54:43 proxmox dnsmasq[95490]: read /etc/hosts - 11 names
Jan 12 14:54:43 proxmox systemd[1]: Started dnsmasq@myNET.service - dnsmasq (myNET) - A lightweight DHCP and caching DNS server.