Stuttering internet on iPhone 16 Pro

Installing and Using OpenWrt
1

I have a strange intermittent problem with stuttering internet, with what feels like occasional high latency when browsing the internet on my iPhone 16 Pro.

The problem manifests as slower loading times (longer spinner animations and delays) of things like browsing this forum on mobile Safari, or trying to load comments on X/Twitter threads, or on YouTube comments. It's a very jarring/frustrating experience.

What is very strange to me is that the problem seems to occur on only one of my two access points in my apartment at a time. When I detect the problem on one of the access points, I can switch over to the other access point by walking towards it and then when the iPhone roams to the other access point, the stuttering goes away and the internet is buttery smooth.

What is also very strange to me is that problem alternates between my two access points. Sometimes the stuttering will be on one of the access points, and then other days/weeks the problem occurs on the other, and sometimes the problem goes away entirely.

I don't perceive the same problem on my other device, a MacBook Pro, and when I run ping and dig on my MacBook and compare between the access points, there is no noticeable difference, yet my iPhone feels horribly slow when the problem occurs.

Does anyone have any idea what this could be or how I could troubleshoot this further?

My setup is:
EdgerouterX with 2x TP-Link EAP245v3's, all on 24.10.1

Some things I've tried:

  • Resetting with very basic/default configs.
  • Reverting to 23.xx firmware.
  • Adjusting wifi channels, widths, cell_density.
  • Turning off all other wifi devices in the house so that its only my iPhone connected.
  • Measuring ping & dns lookup times on my MacBook Pro.
  • Checked logs.
  • Switched access points/cables/POE-adapters.

Wifi config /etc/config/wireless is this on both access points:

config wifi-device 'radio1'
	option type 'mac80211'
	option path 'pci0000:00/0000:00:00.0'
	option band '5g'
	option channel '36'
	option htmode 'VHT40'
	option country 'CH'
	option txpower '20'
	option cell_density '2'

config wifi-device 'radio0'
	option type 'mac80211'
	option path 'platform/ahb/18100000.wmac'
	option band '2g'
	option channel '1'
	option htmode 'HT20'
	option country 'CH'
	option txpower '20'
	option cell_density '2'

config wifi-iface 'wifinet00'
	option device 'radio0'
	option mode 'ap'
	option network 'lan'
	option ssid 'yyy'
	option encryption 'sae'
	option key 'yyy'
	option ieee80211r '1'
	option reassociation_deadline '20000'
	option ft_over_ds '0'

config wifi-iface 'wifinet01'
	option device 'radio1'
	option mode 'ap'
	option network 'lan'
	option ssid 'yyy'
	option encryption 'sae'
	option key 'yyy'
	option ieee80211r '1'
	option reassociation_deadline '20000'
	option ft_over_ds '0'

config wifi-iface 'wifinet10'
	option device 'radio0'
	option mode 'ap'
	option network 'lan'
	option ssid 'xxx'
	option encryption 'psk2+ccmp'
	option key 'xxx'
	option ieee80211w '0'

config wifi-iface 'wifinet11'
	option device 'radio1'
	option mode 'ap'
	option network 'lan'
	option ssid 'xxx'
	option encryption 'psk2+ccmp'
	option key 'xxx'
	option ieee80211w '0'
2

And did it work before enbling 11r?

1 Like
3

iOS does not like mixed either.

4

Mixing no country with country even less

3 Likes
5

Country Code?

6

Yep, 2ghz has world code, and apple in its superior wisdom has all the right to fail roaming.

2 Likes
7

I've updated my original post with revised configs and the problem persists. Country code is now set on both 2g and 5g.

Some more info:

  • Restarting the network interface on the AP which causes the iPhone to be slow makes no difference.
  • Turning the wifi off and on again on the iPhone makes no difference.
  • The problem does not occur on my wife's iPhone 15 Pro, only on my iPhone 16 Pro.
  • Resetting the network configuration on my iPhone makes no difference, will try an entire iOS reset and see what that does.
  • Restarting the 5g radio or clicking on the "Disconnect" button for my iPhone on the wifi client list does resolve the slowness for some time, but it later reappears again.
8

The problem persists with or without 80211r, this does not seem to make any difference.

9

Reduce cell density , remove 5ghz power restriction and set back to default vht80

10

I will try this, thank you. What is your best guess as to what the problem could be? And could you suggest anything else I can check or measure to help troubleshoot the problem aside from configuration changes?

11

Set wifi debug level to 1 (not zero)
https://openwrt.org/docs/guide-developer/debugging#wireless
And try to find event sequence differences between both devices.

1 Like
12

It seems like the problem is with your phone, since neither your wife's iphone nor your Mac is affected. Which network SSID, 'xxx' or 'yyy', is your iPhone set to automatically connect to? It should probably not be both

13

Correct, the problem only seems to occur on my iPhone 16 Pro, not any other device (iPhone 15 Pro, 3x MacBook Pros, an iPad).

My iPhone is only set to auto-join SSID 'yyy'. SSID 'xxx' is only used for IoT devices.

14

Have you compared the wifi settings on your iphones, to see if there is anything different between yours and your wife's? Both on latest iOS 18.4.1?

15

Settings and iOS versions of the iPhones are identical:

  • iOS 18.4.1
  • Fixed private MAC address (the “rotate” and “off” options make no difference)
  • limit ip address tracking is off
16

I checked the wifi specs for iphone 16. It is the first iphone to offer Wifi 7 (802.11be with multi-link operation on 2.4, 5 and 6 GHz). It could be that the problem is not in your phone after all, there may be some unknown incompatibility with your APs.

17

Does the issue also occur on the xxx network?

18

It ususallly makes a difference.

Have you forgotten the network, got the whole thing running for everything else and tried to associate again?

If not:
Go back to defaults (e.g. the MAC default settings)
forget network
reboot
try to associate

Come back.

19

Do you have iCloud Private Relay stuff turned on?

Try keepjng the Private MAC address feature to OFF, no Fixed or Rotating.
I’ve noticed it causes issues especially when there are two SSIDs of the same name.

Try completely turning off Bluetooth on all your Apple devices and testing the WiFi performance as Airdrop and other Bluetooth related features and even system location services are known to cause WiFi latency issues as per

20

Multiple BSSIDs with same name is totally common setup recommended by Apple itself.

2 Likes