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Samsung Galaxy S21 SM-G991
Q&A
User questions and answers about Samsung Galaxy S21 SM-G991
- tips, troubleshooting, and real experiences from the community.
Question 🤔
00
REPO
2026-10-20
I recently replaced the screen on my Samsung Galaxy S21 5G with a replacement OLED display. After the repair, I experienced several issues:
1. Mobile network: Both my physical SIM and eSIM showed “Emergency calls only.” The technician later discovered that a flex cable was missing and replaced it. Mobile network service has since been restored.
2. Wi-Fi reception: The Wi-Fi range has significantly decreased. The phone connects near the router, but when I move farther away, it repeatedly disconnects and sometimes loses the connection. Another phone maintains a stable connection in the same location.
3. Bluetooth: Bluetooth range appears normal.
The technician has inspected the phone but has not identified the cause. I compared the internal layout with a disassembly video for the same model, but I could not identify any obviously missing components.
My questions:
- Which Wi-Fi antenna, coaxial cable, flex cable, or contact points should be inspected on the SM-G991U?
- Could an incorrectly seated antenna contact, missing screw, damaged connector, or improperly fitted internal cover cause this reduced Wi-Fi range?
- What diagnostic tests would help distinguish an antenna connection problem from a Wi-Fi IC or other motherboard fault?
I would appreciate guidance on the most likely causes and the appropriate diagnostic steps before replacing any additional components.
Issue: Significantly reduced Wi-Fi range after screen replacement
I recently replaced the screen on my Samsung Galaxy S21 5G with a replacement OLED display. After the repair, I experienced several issues:
1. Mobile network: Both my physical SIM and eSIM showed “Emergency calls only.” The technician later discovered that a flex cable was missing and replaced it. Mobile network service has since been restored.
2. Wi-Fi reception: The Wi-Fi range has significantly decreased. The phone connects near the router, but when I move farther away, it repeatedly disconnects and sometimes loses the connection. Another phone maintains a stable connection in the same location.
3. Bluetooth: Bluetooth range appears normal.
The technician has inspected the phone but has not identified the cause. I compared the internal layout with a disassembly video for the same model, but I could not identify any obviously missing components.
My questions:
- Which Wi-Fi antenna, coaxial cable, flex cable, or contact points should be inspected on the SM-G991U?
- Could an incorrectly seated antenna contact, missing screw, damaged connector, or improperly fitted internal cover cause this reduced Wi-Fi range?
- What diagnostic tests would help distinguish an antenna connection problem from a Wi-Fi IC or other motherboard fault?
I would appreciate guidance on the most likely causes and the appropriate diagnostic steps before replacing any additional components.
REPO
2026-10-20REPO
2026-10-20