The S25 supports Wi-Fi 7 and WPA3, and the faults owners describe come from that pairing rather than from the phone's antenna: the S25 drops to mobile data, or crawls at 1 Mbps, on a Wi-Fi 7 or WPA3 router, while the same phone holds on Wi-Fi 6 with WPA2. Forget the network, update the router firmware, and try the router's 5 GHz band with WPA2/WPA3 mixed mode before you reset anything on the phone.
Differential
Likely causes of “Samsung Galaxy S25 will not connect to Wi-Fi or keeps disconnecting”, and how to tell them apart
- 1
A Wi-Fi 7 or WPA3 mismatch with the router
What separates it Connected but no internet, or speeds of 0 to 1 Mbps, while other devices are fine
How to confirm Switch the router band to WPA2/WPA3 mixed or WPA2 on 5 GHz and rejoin; if that works, update the router firmware
- 2
Intelligent Wi-Fi switching to mobile data
What separates it The phone drops Wi-Fi in the same room and the Wi-Fi icon blinks
How to confirm Settings, Connections, Wi-Fi, Intelligent Wi-Fi: turn off Switch to mobile data and Auto switch between Wi-Fi networks
- 3
A saved network with stale details
What separates it Other phones join, this one reports Authentication problem
How to confirm Forget the network and join it again with the password typed fresh
- 4
Random MAC address or IP setting
What separates it A work, school or guest network blocks the phone
How to confirm In the network's Advanced options set MAC address type to Phone MAC and try once
- 5
A router that is busy or old
What separates it All devices slow at the same hour
How to confirm Restart the router, move it clear of the microwave, and try 2.4 GHz for range
Before you touch a setting
Record this first — changing settings destroys the evidence
- Router make and model, and whether the band is 2.4, 5 or 6 GHz
- The error on screen: Authentication problem, Connected without internet, or no networks
- Whether another phone joins the same network
- One UI version and security patch date
Try in this order
0 of 6 completedRestart both ends
ReversibleRestart the phone and the router. Wait two minutes after the router's lights settle before rejoining.
Forget and rejoin
ReversibleSettings, Connections, Wi-Fi, tap the gear beside the network, Forget, then join again.
Turn off Intelligent Wi-Fi
ReversibleIn Wi-Fi, three dots, Intelligent Wi-Fi, switch off Switch to mobile data and Auto switch between Wi-Fi networks; both can drop a working link.
Test WPA2 on 5 GHz
ReversibleIn the router's admin page set 5 GHz to WPA2/WPA3 mixed or WPA2 and turn Wi-Fi 7 or MLO off if the router lists it. If the S25 now holds, the combination was the fault.
Update the router
ReversibleRouter firmware often fixes Wi-Fi 7 handshake faults; check the maker's app or admin page.
Reset network settings last
Reset / data riskSettings, General management, Reset, Reset network settings clears Wi-Fi, mobile and Bluetooth settings, and often fixes a corrupted profile.
Stop boundary
When this stops being a self-service repair
- !If every network fails in Safe mode and after Reset network settings, book a Samsung hardware check
- !If only one router fails, call that router's maker or your provider; the phone is fine
- !If Wi-Fi is grayed out and will not switch on, restart once and then book service
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Does the S25 support Wi-Fi 7?+
Yes, all three S25 phones list Wi-Fi 7 and Bluetooth 5.4, but it only helps on a Wi-Fi 7 router.
Why does my S25 say connected but there is no internet?+
A router, DNS or WPA3 fault upstream of the phone. If the same network works on a laptop, try the WPA2 test and Forget and rejoin.
Is 2.4 GHz or 5 GHz better on the S25?+
5 GHz is faster at close range; 2.4 GHz reaches farther. If the phone drops at a distance, try 2.4 GHz.
Will resetting network settings delete my data?+
No photos or apps are removed, but saved Wi-Fi networks, mobile settings and Bluetooth pairings are.