Two OPenWRT Devices in same subnet cant ping each other, but all orher devices can?

Installing and Using OpenWrt
1

Hello!
I have a VERY weird problem. I have 4 OpenWRT devices in my house, one Flint2 with 24.10.1 as main router and some NeWifi D2 as dump access points. The Flintt2 replaced a WRT32000ACM recently and I rebuild my config mostly from scratch. As for now evrything is working, but the APs ar running older versions of OpenWRT. The AP's are directly connected via LAN to the main router.
So i took one, flahsed the newest release and wiped the config.
Now comes the strange part :slight_smile:
I only deleted the WAN interfaces and changed the static IP of the default br-lan interface on the AP so it lies in my subnet. Now i am able to access the AP and the main router from my PC in the same subnet without problems. Both devices can ping and access IP adresses from different devices in that subnet, too. BUT: they can't reach each other. ARP shows MAC and IP fine, but for some reason no communication is possible.
I thought it might be a problem with the newest OpenWRT release but flahsing older variants acts the same.
My other NeWifiD2 is still on 22.03.05 and works as expcted.
I have no idea what's happening....

even weirder: I took a backup from my working AP, replaced the IP and the name in the backup file and restored it to the second AP. Still the same problem.....

2

Check you settings with the BridgedAP wiki

Make sure you also set a DNS address and gateway at the LAN interface of the AP (ususaly pointing to your main router)

3

GW and DNS are set, but even if not, a ping in the same subnet should still work. After trying to PING the target IP and MAC show up in the arp table on both devices.
The same config, only with a different IP in the sane subnet works as expected on another device. Even this AP worked before with the same config, what is really strange... I am starting to believe that there is no error in the config but something weird is happening in my home network.

4

Hmmmm, just redid the configuration and gave my AP a DIFFERENT IP in the same subnet and now its working................... I have NO IDEA whats going on here :slight_smile:

5

Duplicate IP addresses?

6

Its the same IP the device had before i flashed it new, and it's outside my DHCP pool range. I just checked again, the old IP isn't used anywhere now. I suspect some ARP weirdness.

I now will try the next AP and see how that behaves.