Samsung
Turn On Wi-Fi Sharing (Wi-Fi Repeater Mode) auf Samsung
Samsung phones can work as a Wi-Fi repeater, but only if two conditions are met at the same time. First, the phone must already be connected to a working Wi-Fi network. Second, the Mobile Hotspot must have the Wi-Fi sharing option switched on, since this is what tells the hotspot to forward the existing Wi-Fi connection instead of the mobile network.
Without an active Wi-Fi connection on the phone itself, the Wi-Fi sharing switch stays greyed out and the hotspot falls back to sharing mobile data only. This is the most common reason the repeater mode appears to be missing.
To reach the setting, go to Tap on Settings ➔ Tap on Connections ➔ Tap on Mobile Hotspot and Tethering ➔ Tap on Mobile Hotspot ➔ Tap on Configure ➔ Tap on Advanced. From there, use Enable or disable Wi-Fi sharing, confirm with Tap on OK, then Tap on Save to apply the change.
Once enabled, every device joining the hotspot uses the phone's Wi-Fi bandwidth. Expect slower speeds if several devices connect at once, since all traffic now passes through a single Wi-Fi link instead of a separate mobile connection. If your Wi-Fi signal is weak or unstable, sticking with the normal mobile-data hotspot is usually the more reliable option.