Can you try the SmoothWAN 0.99.8 version, it’s got a much more recent kernel and Wi-Fi drivers. I couldn’t replicate it locally (no ios).
Need to setup WPA3 sometime soon for more testing, you may have to force WPA3 only instead of mixed connected to the iPhone.
Running out of memory on system crashes the Wi-Fi radio as well as other services. But this doesn’t seem to be the case here.
0.99.8 goes back from SmoothWAN v0.99.5HF5 / LuCI openwrt-22.03 branch git-21.284.67084-e4d24f0
which I am running currently, pleases confirm… I will do so if that is the case…
Ooh that’s a typo 
it should be 0.99.9HF5.
Yes that’s correct.
I am attempting to upgrade but there is no upgrade option in the system → backup/flash firmware → actions tab → flash new firmware image I am receiving this error “Upload request failed: I/O failure while writing temporary file”
So I was able to upgrade using the downloaded file from 0.99.9HF5 after a router reboot. Though are we sure that what was posted is labeled correctly as the router after the update shows 0.99.5HF5.
Im considering restoring the default firmware and starting from scratch, but before I make that effort can you check if the currently posted version is correct regardless of the filename?
Apologies for the confusion, I meant that the LuCI dashboard was showing 0.99.5HF5 instead of 0.99.9HF5, there is no 0.99.5HF5.
You can flash 0.99.8 for testing.
The I/O failure is probably caused by latest Speedify (13.3) running and using a bit more RAM than the usual unlike with the older versions, try stopping it before flash. (the image is uploaded to RAM, and it’s quite large)
Understand but it is the latest version… the original was bit for bit the same. so you .99.9hf5 is report .99.5
Sorry, missed the reply, yes I meant you could downgrade. I’ve had multiple reports from GH regarding this issue with iOS, next version will use WPA3 only & WPA2 only in the menu, in the meantime you can change that setting in the Wireless menu.
I’m having similar issues with the similar devices (home router and iOS 17 tethering) and fumbled on this thread. I’ve even somehow managed to get both of my Master devices to disappear so I can’t connect to my Slate anymore trying both bands, really sucks 
At first I thought my Slate was bad but luckily I had another to try Amazon accidentally sent me 
I’m trying to understand what to keep an eye out when connecting these Client wireless connections to avoid this problem are we thinking it’s an issue with the frequency or the channel?
By the way is there any reason to avoid WPA3, it seems like Simple Wi-Fi prefers WPA2 only?
WPA3 works fine, but “SAE-Mixed” which is WPA3/WPA2-mixed seems to be problematic.
You can reset SmoothWAN on the Slate/Flint by holding the reset/WPS button for 10 seconds, after release the device should restart in few seconds.