Direct answer: If your iPhone can’t connect to this device (Bluetooth, Wi‑Fi, or USB connection), try these steps in order to restore a working connection. I’ll outline common causes and practical fixes, then you can tell me which device you’re trying to pair or connect with for more tailored steps. Key fixes you can try now

• Ensure the device is in pairing or discoverable mode
  • Bluetooth: Put the accessory in pairing mode and confirm it appears in Bluetooth settings. Restart Bluetooth on the iPhone if needed.
  • Wi‑Fi: Make sure the other device is on and connected to the same network, or try reconnecting after a restart.
  • USB: Use a different cable and a different port if available; ensure the device is trusted on the iPhone if prompted.
• Restart and refresh
  • Restart the iPhone: hold the side button and either volume button, then slide to power off; wait a moment, then power back on.
  • Restart the other device (accessory, router, computer) as appropriate.
• Toggle wireless settings
  • Bluetooth: Turn Bluetooth off, wait a few seconds, then back on.
  • Wi‑Fi: Turn Wi‑Fi off, wait a few seconds, then back on. Reconnect to the correct network.
• Forget and re-pair or re-join
  • Bluetooth: In Settings > Bluetooth, tap the device name and choose Forget This Device, then pair again.
  • Wi‑Fi: In Settings > Wi‑Fi, tap the network, Forget This Network, then reconnect with the password.
• Reset network settings (last resort)
  • Go to Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings. Note this erases saved networks, VPNs, and Bluetooth pairings, so you’ll need to reconfigure afterward.
• Update software
  • Check for iOS updates in Settings > General > Software Update and install if available; updates often fix compatibility issues with accessories and other devices.

If the issue persists, tell me:

• Which device you’re trying to connect (exact model if possible)
• Whether the problem is with Bluetooth devices, Wi‑Fi networks, or USB connections
• Any error messages you see on the iPhone or the other device

With that, I can provide device-specific steps (and, if needed, model- or scenario-tailored instructions).