Internet speed slow down after IOS 17.1 update

You can try these Steps, hopefully it will help you out:

1. Check your Wi-Fi or Cellular Connection: Sometimes, slow internet is due to your network. Make sure you have a strong Wi-Fi or cellular connection. If possible, switch between Wi-Fi and cellular to see if one works better.
2. Reboot Your Device: A classic solution! Restart your iPhone by holding down the power button and swiping the slider to turn it off. Then, turn it back on.
3. Reset Network Settings: If the issue persists, try resetting your network settings. Go to Settings > General > Reset > Reset Network Settings. Be aware that this will reset all your saved Wi-Fi passwords and network settings.
4. Check for Updates: Sometimes, Apple releases updates to fix such issues. Check for any available iOS updates by going to Settings > General > Software Update. If there's an update, download and install it.
5. Contact Your Internet Service Provider: If none of the above works, it might be an issue with your internet service provider. Reach out to them to check if there are any problems on their end.
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Hopefully, one of these quick fixes will help you get back to faster internet speeds.