Wi-Fi connection and speed on my iPhone 15 Pro degraded post iOS 18.1.1 update.

What about: Do you have a 3rd party VPN installed? If so, delete the VPN profile in Settings/General/VPN & Device Management/VPN. Don't just turn it off; delete the profile. If that fixes it, you can try reinstalling VPN.

And you said you had the same issue, but your issue is different because alxsim843 only had a Wi-Fi problem not both Wi-Fi and 5G.

Carter151 wrote:

I did not reboot the router, and I have never before experienced this issue on my home Wi-Fi network. While experiencing this issue, other family members running 18.1.1 on their older model iPhones did not have any internet or data connectivity issues. Unfortunately (?) I was unable to test connectivity with other Wi-Fi networks to see if the problem persisted. It has been 24 hours since the issue mysteriously resolved itself and I am grateful the connectivity problem hasn't resurfaced.

OK, here is the explanation of why I suggested rebooting your router, but it is up to you if you want to try:

Wi-Fi normally connects to a router, which assigns an IP address using a protocol called DHCP (Dynamic Host Configuration Protocol). But it’s possible to also use Wi-Fi to connect a group of devices to each other rather than to the Internet in what is called an ad-hoc network. Ad-hoc networks use IP addresses in the range that starts with 169.254.0.0. Each device in the ad-hoc network creates its own IP address in this range. When you connect a device to a network it will "ask" the router for an IP address using DHCP. If it doesn’t get an IP address assigned within 30 seconds it assumes that it is an ad-hoc network and assigns itself a random address in the range 169.254.x.y.

There is a common failure mode in many routers where the DHCP “daemon” process in the router fails, and it stops assigning IP addresses, so a new device connecting to the network will self-assign. But any device connected to the router that already has an IP address will continue to work. This makes it look like the problem is the phone, because everything else connected still works, but it’s actually the fact that the router is no longer assigning IP addresses. While it can happen to any device using the router the problem is more common with phones that disconnect when they go out of range, and reconnect when you get “home” and thus get a new IP address assigned. Rebooting the router restarts the DHCP daemon and resolves the problem.

The reason it happens with many different routers is that most routers have the same underlying open source operating system. It’s primarily a problem with routers more than a few years old; newer ones from top tier manufacturers rarely have this problem.

Not I.

First step is to restart your router, even if it is working for 100 other devices. Unplug it from power for about 15 seconds. (If you are interested I’ll post the long answer and reason, but for now I recommend you just do it).

Also: Do you have a 3rd party VPN installed? If so, delete the VPN profile in Settings/General/VPN & Device Management/VPN. Don't just turn it off; delete the profile. If that fixes it, you can try reinstalling VPN.

I think resetting the router and resetting settings on the phone helped

I have the same issue over wi-fi and 4g/5g. The only cure is to power down the phone and reboot again. It’s working for a while and then the same again. I hope they will fix that quickly.

Device: 16 Pro Max

iOS: 18.1.1

Issue: Settings/WiFi indicates connected to home wifi but the wifi icon is not displayed in the upper right corner. The App Store failed to load after cycling the wifi toggle off/on during the initial trouble shooting process

Steps Taken 1: WiFi was disabled and connected to AT&T 5G. Problem persisted.

Steps Taken 2: Closed all applications and performed a hard reboot. Problem persisted.

Steps Taken 3: Reset network settings. Reconnected to wifi. Problem persisted.

Steps Taken 4: Resolved to visit the Apple Store the next day and set the phone on the nightstand. 5 minutes later the sound of notifications alerted me to the now functional wifi connection. WiFi indicator now present in upper right corner and the phone functions properly... for now.

Did you try rebooting your router. Does it happen with one Wi-Fi network or all Wi-Fi networks?

18.1.1 has completely ruined my phones WiFi and 5g speeds downloading anything has been horrible! Random apps are crashing or system performance is not allowing me to go back and forth between them. Serious issues still exist with gaming mode causing lag with controllers and Bluetooth headphones. Battery life has been complete **** when using basic functions of the phone. I did a complete reinstall when installing 18.1.1 through iTunes and wiped my data completely off the phone. So this by definition was a fresh install of the operating system and I’m still dealing with serious bugs and battery life issues. I have no indexing warning on battery, I did how ever loose two percent battery life a week back randomly at 208 charges. I firmly believe apple is doing a lot of this nerfing to the iPhone 15 max and it’s counter parts to force people into upgrading to the 16 that did horrible.

I did not reboot the router, and I have never before experienced this issue on my home Wi-Fi network. While experiencing this issue, other family members running 18.1.1 on their older model iPhones did not have any internet or data connectivity issues. Unfortunately (?) I was unable to test connectivity with other Wi-Fi networks to see if the problem persisted. It has been 24 hours since the issue mysteriously resolved itself and I am grateful the connectivity problem hasn't resurfaced.

I just restarted my router and my iPhone settings after just doing a clean install of iOS 18.1.1 through iTunes a few days back idk how either which of these things would impact my WiFi or cellular data I had already reset network settings after clean install as well

I am having the same issue and have an iPhone 15 as well

Did you see my answer to alxsim843? Have you tried those suggestions?

Sorry to say but similar thing happening on 16 Pro Max. So may need tweaking in the next update

Strange, then, that my family's iPhones on 18.1.1 still perform as well as they ever did on my Wi-Fi and 5G connections:

Wi-Fi (on FiOS 940mbps connection):

5G: