Thanks for the question. I understand the Wi-Fi connection on your iPhone 4S drops unexpectedly. That definitely sounds frustrating. The following article provides some troubleshooting steps that may help to resolve your issue:
Wi-Fi disconnects, or signal strength is less than expected
- Move closer to the Wi-Fi router (access point).
- Check for sources of potential interference.
- Remove any case, stand, or other accessories from your iOS device and see if signal strength improves.
- Reset network settings by tapping Settings > General > Reset > Reset Network Settings.
Note: This will reset all network settings including: previously connected Wi-Fi networks and passwords, recently used Bluetooth accessories, VPN and APN settings.