My internet connection delivers around 250 Mbps to the router, but after updating several household Apple devices to OS 27—and one iPhone to OS 26.7—their Wi‑Fi speed tests dropped to roughly 50–60 Mbps. The issue affects a MacBook Air with an M2 chip, an iPhone Air, an iPhone 15, an iPad mini 7th generation, and an iPad Air 4th generation. A Windows laptop on the same network still reaches the full 250 Mbps.
I tested with Speedtest through Safari on each device and also used the app on one iPhone. Forgetting and reconnecting to the Wi‑Fi network did not help, and iCloud Private Relay is disabled. Has anyone experienced this, or found a reliable fix?
Update: The cause was a compatibility problem between the new operating systems and an Eero 6 router using WPA3-only security on its 5 GHz band. Changing the 5 GHz network to WPA2/WPA3 hybrid mode, matching the 2.4 GHz band, restored the normal speeds. The Apple devices still connect using WPA3.
3 Answers
Try disabling the Wi‑Fi connectivity assistance option in the network settings. That fixed a similar slowdown for me after updating to OS 27.
On my iPhone, the test started a little slowly but reached the usual speed after a couple of seconds. You could try changing DNS settings, rebooting the affected devices, and checking whether background updates or downloads are running. Also compare both the 2.4 GHz and 5 GHz networks.
Those checks didn’t resolve it, but I found the answer: the new OS versions didn’t work well with my Eero 6 using WPA3-only security on 5 GHz. Switching that band to WPA2/WPA3 hybrid mode brought the speeds back to normal.
I haven’t seen any slowdown on my devices. It may be worth checking whether the speed test is measuring the internet connection rather than the link speed to the router, and comparing results across different bands or devices.
That setting was already disabled in my case. I eventually found the problem was a compatibility issue between the update and my router’s WPA3-only configuration.