iPhone seems to be slow to resolve DNS after installing OpenWrt

[Wuzizname]

Hi everyone. First off, thanks to this great community for doing what you do, OpenWRT is nothing short of amazing.

I just upgraded my D-Link DIR-2640 router to openWRT over the weekend and everything is working great except for the wireless connection to my iPhone 8. It seems to be having a hard time bringing up webpages, feels like it's having a hard time resolving DNS as once the page does load it loads fast and I've also done speedtests on the phone and get consistant 150 mbps speeds which is my bandwidth limit with my ISP.

All of my other devices, both ethernet and wireless, all work great. It's just this phone.

I looked at some articles online about forcing your iphone to "Forget Network Settings" which I've done twice now to no avail. Also set the phone to use the router IP as the DNS setting, no luck.

Anyone here have any advice? Specs below:

DIR-2640 D-Link router
iPhone 8, ios ver 14.6
Router DNS is pointed at openDNS as primary with Google as secondary, for both IP4 and IP6

Thanks in advance!

[Wuzizname]

Still experiencing this unfortunately. Is there anyone about who could verify the dns settings I’m using I’d super appreciate it?

[vgaetera]

Check if the problem persists with the following configuration:
https://openwrt.org/docs/guide-user/base-system/dhcp_configuration#upstream_dns_provider

[Wuzizname]

This looks like what I’ve set through luci but will try via ssh as well. Thanks for the resource.

[CharlesJC]

@Wuzizname did you install openwrt 19.7 or 21.02-rc?
I had a similar issue as yours on 21.02-rc3. My workaround was fairly drastic, I disabled external IPv6 (WAN6) but I’m planning to look at the workaround suggested above by @vgaetera to see if that works for my configuration

[Wuzizname]

Here’s what it says on the router login. Seems I am in 21 as well.

OpenWrt 21.02.0-rc1 r16046-59980f7aaf

[IanC]

You could set a static IP address and / or DNS for the iPhone for a test. Try the same DNS entries that it gets from DHCP and something else like OpenDNS. Then you should be able to tell. You could also put some packet sniffing on the router to see if there is a delay, dropped packets, etc.

[mike]

Do either of you @Wuzizname @CharlesJC have software flow offloading enabled by chance? I've had similar problems on 21.02.* and snapshot (made this bug report a few days ago) and noticed that the problem went away by a) disabling software flow offloading or b) disabling ipv6 when software flow offloading is enabled.

[CharlesJC]

I checked. I did have this setting set. I disabled it, restarted the Wan6 interface, and my terrible network experience resumed. So this is not related to the issue that I have. I disabled Wan6 and I could browse again from phone again.
But thank you for the suggestion.

[Wuzizname]

@vgaetera Worked like a charm. I set both a static IP for the Iphone and followed the instructions that you sent and I'm back to smooth sailing. Thanks very much!