Xperia 1ii disconnects from 5G to 4G+

[aaljuma]

Hi, I've been using the phone for a while. However, the 5G network doesn't seem to connect. It does when you swap the sim card with a different one, and after 10min it goes to 4G+ for some reason, and it's stuck there until you swap the sim, and the loop keeps going. It never seems to stay 5G.

Yes the phone is in it latest update.

Yes the SIM can connect to 5G. (tested on other 5G devices)

Yes I have a 5G plan.

Yes I have tested this while literally standing under a 5G node.

Yes my service provider supports the 5G bands of the Xperia 1ii.

Yes I've tried multiple sims.

Yes I have contacted my service provider, and they say everything seems fine from their end of things.

Yes I have restarted, and factory reset my device multiple times.

Nothing seems to work too keep my 5G phone stay connected to 5G.

[RottenFoxBreath]

If its not stable, it'll drop to the next stable network speed.

What selection on network settings/preferred network, do you have picked?

In my city, 3 and Vodaphone state stable 5G but it's spotty on both, to be honest, it's really bad.

o2 is the best, which I went for, even though the others say theirs is fine, it's really not.

[aaljuma]

I have a WiFi Mobile 5G router to test the connection. That seems to have a more stable connection in the same spot than my Xperia phone. Actually it’s consistently connects to 5G.

I’ve got the Preferred Network Type to: 5G/4G/3G/2G

[Jess.09]

Try to select the preferred network type to 5G only, from Settings → Network & Internet → Mobile network → Preferred network type. Select 5G only.

[aaljuma]

Hi @Jess.09 

I’m afraid there’s no 5G only choice for some reason.

[RottenFoxBreath]

Totally different from my options.

[aaljuma]

Interesting 🤔
Obviously we don’t have the same experience using the same device. Hopefully someone from Sony can help clarify what’s going on here. 

[Jess.09]

If the 5G network is not stable, it will automatically switch to other networks.

Try to contact your operator again, they may be able to help.

[MJ_QaTaR]

Unfortunately I have the exact same problem and yet to find a solution.

The 5G network is strong, using other 5G devices I can get an average of 480 Mbps download speed, while being at the same spot I can only connect to 4G+ with my xperia 1 ii.

And it used to work, flawlessly with 500+ Mbps download speed but it stopped working all of the sudden. I did all what @aaljuma did, still couldn't connect to 5G network.

[Jess.09]

I believe that depends on the stability of the 5G network in your area, if it is not stable it will switch automatically to other networks.

Did you try to contact you network operator?