My primary router is an ISP issued Compal CH7465LG-VM. I have little control over advanced settings but it handles all DHCP and I have set reserved IPs for all hubs and bridges. I've had this router for about 2 years with no problems and the Alien for about six months. Added it after moving home and needed to get WiFi into the far corners of a larger home, without using a mesh. Have had mixed results in the past with Homekit and mesh networks. The Alien router is in bridge mode and is connected directly to the ISP router. It's the only connection to the ISP router. All wired devices go through an ethernet switch to one of the ethernet ports on the Alien router. Connected to the switch are the ATV (used as preferred home hub), an IKEA bridge, a WD NAS, a Sonos Boost and a cable TV box. Everything else is wireless and all WiFi traffic goes through the Alien router also. Everything is on the same local area network and both the 2.4GHz and 5GHz radios use same SSID with fixed channels and on the least congested channel I could find. My Home set-up has always used the same SSID for almost 10 years now, of using Homekit, so no changes there either. I'm planning on changing ISP provider after Christmas but I'll try get the logs done before that with current set-up and if the issue persists (I'm really hoping it's my ISP router), I'll go again. In my case there are two devices showing this behaviour. An iPhone 12 on iOS 26.2 and an iPhone 15 on iOS 26.2 and one device that doesn't show this behaviour - an iPhone XS on iOS 18.7.2. All home hubs are on iOS 26.2. Native apps for my Homekit devices all work fine (IKEA, Meross, Eve, Aqara, Fibaro) both locally and remotely. But I've been able to reproduce the issue outside of the Home app. Yesterday, I downloaded and installed an app called HomeCare. Opened Home app to confirm my home hubs were showing as not responding. Ran HomeCare diags in quick mode, HomeKit Hub showed as disconnected, 130 Faulty Devices. Re-ran diags, Home Hub connected, 90 faulty devices. 3rd run, Home hub connected, no faulty devices Returned to Home app and all was was good there. Waited 30 minutes, Home app showing all hubs are not responding again. Use the HomeCare diags to give the hub a bit of a kick, and they're back. No worries, re. expectations. I'm not expecting any quick fixes over Christmas. I've learned to live with it. Everything else is working (expect arriving/leaving automations which 26.1 did not fix for me, but I've worked around that too).

Same issue here... FB20940178 Started on iOS 26 and continues through 26.1 and 26.2. Prior to iOS 26 update, performance was solid (>120 devices). Issue is present when using Home app on local network at home or when accessing remotely over cellular network. Issue is present on two iOS 26 devices. Network set-up is an ISP router with AmpliFi router connected in bridge mode as a WAP. No mesh points. No network changes before or after update. All hubs updated, same OS version. All hubs have reserved IP addresses. Re-started router. Re-started hubs (wired ATV, HomePod Minis). Tried setting Preferred Home Hub to each of the six available hubs. Tried using Automatic Selection. Reset network settings on iOS26 devices. Have one older iPhone XS that's still on iOS18.7.2 and it works fine.