Hi，@philippe_44 

Currently, Omada does not support configuring multiple DHCP reservations for the same MAC address across different VLANs. This is more of a limitation resulting from product implementation, rather than a restriction at the network layer. The root cause can be explained from the following aspects:

1.The DHCP reservation feature was designed early on, primarily for the common scenario of one device connecting to one network. The use case where the same MAC exists on multiple VLANs simultaneously was not taken into account in the initial design. Therefore, the matching logic for reservations uses MAC as the unique identifier, instead of taking Network/VLAN + MAC as a composite key. This design works properly in the vast majority of scenarios, but it cannot accommodate the usage pattern you are currently adopting.

2.In addition to completing DHCP address assignment, the Omada Gateway also needs to uniformly report client information to the Controller for centralized management. For the Controller, the same MAC address is usually identified as one single client. Allowing the same MAC to have different reservations, IP leases and status information across multiple networks would add extra complexity to the logic of client identification, data synchronization and management.

Therefore, we believe this issue is more appropriately defined as a current product implementation limitation, rather than "this scenario is unreasonable" or "unsupported by network protocols. 

We fully recognize that this is a legitimate and practical real-world usage scenario, and we will feedback this requirement to the relevant internal department for evaluation. Thank you very much for your valuable feedback.

  @Nathan-TP - Thanks for your reply. I'll set a local MAC address for these units' VLAN then. Just one comment: the DHCP works and assigns an address for each VLAN, the only thing missing is the reservation. I don't know if that creates a mess for Omada controller MAC/IP/Devic database, but I did not observe a problem. Still, this is a bit weird for an entreprise-grade system but I guess this is one of these technical debts that nobody wants to hear about