Xiaomi
Turn On or Off Dual 4G auf Xiaomi
On many dual-SIM Xiaomi phones, only one SIM slot gets a 4G connection by default while the second one falls back to 3G or 2G. This happens because the modem hardware can only maintain one high-speed data connection at a time unless Dual 4G is turned on.
The Dual 4G option controls whether both SIM cards are allowed to negotiate a 4G connection simultaneously. Turning it on usually improves call and data quality on your secondary SIM, but it can slightly increase battery use since the modem works harder to keep two 4G radios active.
Not every Xiaomi model exposes this setting. If your phone lacks a Dual 4G toggle, the modem hardware simply does not support dual VoLTE or dual 4G standby, and no software update will add it.
To change the setting, go to Tap on Settings ➔ Tap on SIM cards & mobile networks ➔ Enable or disable Dual 4G. If one SIM still shows a weaker signal after enabling it, check that both SIM cards are inserted correctly and that your carrier supports 4G in your area.