I've been using OpenWrt across my home network for 2 years or so now with OpenWrt 21.02.x, upgrading through the releases. I have a typical home VLAN set up. 3 VLANS, 2 (lan), 3 (GuestNet) and 4 (IoT). I have a main OpenWrt firewall router (RPi400) that manages the traffic to the WAN and between the VLANS and DHCP servers, one for each interface, for the three VLANS. I also have 3 BT HomeHub 5A as wifi access points around the house also configured with OpenWrt and the same 3 VLANS and associated wifi networks (Abwehr(2), GuestNet(3) and IoT(4)). The RPi400 and each BT HH5A connect to a SmartSwitch via their single tagged (trunk) ethernet port. Everything else connects to any one of the wifi networks or an untagged port on a smart switch and so ends up on the right network according to the wifi network, switch port PVID and VLAN associated to it. For two years it's run without a hitch. I couldn't remember the last time I had to reboot anything. As reliable and reliable could be.
I have no use for IPv6, my ISP doesn't support it and so I disable IPv6 on the respective devices.
However, I changed my ISP to something faster and so thought I'd take the oportunity to update everything to as current as possible OpenWrt, and implement DSA for each of my HH5A devices to 22.03.6, a TP-Link ArcherA7v5 to 23.05.2 (which is still not DSA). These are my access points. The RPi400 (23.05.2) firewall router is also new and also DSA implemented. Let the nightmare begin.
I've been able to determine after a very great deal of pain (because the ArcherA7v5 works fine and so confusing things) that the BT HH5A's are not passing the DHCP requests from their wifi access point to the interface, to then go across the network to the RPi400 DHCP server. Oddly, if the Tablet or phone or laptop or whatever manages to get an IP address via the Archer A7v5, it can then switch to a closer HH5A and carry on OK, however without getting an IP address, the connection just fails. I'm pretty sure the config as seen from Luci is right. I'm at a loss as to see where the issue is or how to troubleshoot. Under 21.02.1-7 the HH5As have worked without a hitch. Having installed 22.03.6 and reconfigured using DSA (the switch menu option is no longer present) despite attaching the wifi access to the Interface, it doesn't work on any of my HH5A's and I'm having to roll back 2 of my three HH5A to 21.02.6 whilst trying to figure things out on the third.
Advice on what to do next please.
