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As in the diagram below I have two routers on two different subnets. I connected them together but have not set static routes yet.

Network Diagram

However, when connecting from Access Point A's SSID, I get an IP from Router B on its network (192.168.2.x), and when connecting via Access Point B, I get an IP from Router A (192.168.0.x). Also, the DHCP relay function is disabled on Router A (EdgeRouter X), but didn't find that option on Router B (TP-Link R470T+).

How to make sure only the DHCP server on the same network responds to DHCP requests? I am trying to block UDP ports 67/68 on the outgoing interface of the Edgerouter without any success so far, but I hoped there might be a more straightforward solution.

Thank you.

Reedz
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    so AP A **always** gives a router B address and AP B **always** gives a router A address? perhaps your network is *actually* wired with AP A connected to Router B and AP B connected to Router A? That would definitely produce the result you're apparently observing - try swapping AP's around – Jaromanda X Jul 12 '23 at 08:30
  • @JaromandaX The AP are definitely connected to the right routers (the individual networks have always been separate before and the AP's SSID are distinct to each network) – Reedz Jul 12 '23 at 09:42

2 Answers2

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Without a relay, it's not possible for a DHCP server to respond to DHCP discoveries/requests from another subnet / layer 2 segment.

DHCP discovery or request are sent to the (limited) broadcast address, and broadcasts are not forwarded by a router.

The situation you describe is only possible when there is a relay (consumer routers don't relay) or when your diagram is incorrect.

Zac67
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I found the issue was due to misconfiguring the IP address of the Edgerouter interfaces, now all is working as it should, thank you.

Reedz
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