Here’s my solution to avoid the bug on my Fairphone 5 in Switzerland with the Salt network, which uses NSA 5G. Every time I switch from a 4G to a 5G tower, the internet connection drops since I activated VoLTE. This bug is easily reproducible by activating VoLTE and selecting “4G/3G/2G” then “5G/4G/3G/2G” in the Preferred Network Type. Here’s the solution: Enable “Developer options,” search for “Prefer 5G NR Mode,” and then switch from “NSA+SA Mode” to “NSA Mode.” This resolves the bug and also enables voice calls over 5G.
The only thing you have done with switching to the NSA Mode is to disable 5G SA completly. So you have not enabled VoNR you are now using VoLTE for all calls, because in the NSA Mode all calls go through the LTE Anchor and the 5G NSA Band is diconnected while you are calling. Maybe the 5G SA Network is causing your problems.
You’re right, but with your method I lose access to 5G. It would be simpler if Fairphone fixed this bug because if you make a call to the number *#*#4636#*#* you’ll see that the “ignore network type: NR_NSA” option is enabled, which is probably the cause of the problem. My modification in the “Developer options” is the solution because most networks temporarily use 5G NSA to save time and money.Furthermore, I don’t lose access to 5G.
If it is a bug, report it to support so they can forward to developers. The company does not always check here and will probably never be addressed if only posted in the forum unless they find it too.
The only thing i want to make clear is that you don’t use Voice over New Radio (5G) when you use 5G NSA. VoNR is only used when you are connected to the 5G SA network. So your call is over the 4G Network (VoLTE) and the 5G NSA Band is disconnected while you are calling. After the end of the call the 5G Band is reconnected again. The network Indikator normaly stays on 5G even while you are calling, you can observe the disconnect of the 5G Band with apps like Netmonster. With normal smartphone use you will not even notice this change so it makes no difference.
Unfortunately, if I don’t enable VoLTE, my calls are made over 3G (confirmed by Netmonster).
And since 3G is often unavailable, I can no longer make calls everywhere.
That’s why selecting NSA only in the developer options is essential, as it allows me to make calls over 4G with Volte and avoid data connection drops when switching from 4G to 5G.
I should also mention that this problem exists with other carriers.
That is correct when you disable VoLTE the phone use 2G or 3G for calling. When both is not available it is not possible to place a call with disabled VoLTE. What is not working when the 5G NSA/SA mode is selected? No data connection or only no calls or both? Does the phone try to connect to the 5G SA network? Is 5G SA possible with your carrier? If 5G SA is not possible with your carrier than the NSA only mode is better (the most carriers only offer 5G NSA).
Finally, I reported this bug to the Fairphone developers and a support ticket has been registered.
I hope the problem isn’t my phone.
I tried with a SIM card from another operator (Swisscom) that doesn’t offer 3G, and the problem disappeared.
With my current operator (Salt) and all other operators that still offer 3G, the only way to resolve this bug is to:
Enable “Developer options,” search for “Prefer 5G NR Mode,” then switch from “NSA+SA Mode” to “NSA Mode.” This resolves the internet connection loss bug and also enables voice calls over 4G LTE.I also noticed when dialing ##4636## under “Phone information” that the “Ignore network type: NR_NSA” option is enabled. Could this be the cause of the problem?