Weak (no bar) 3G signal after back from 2G

Anyone with Android 6.0 experience this issue?

So, when the phone enters an area with weak 3G signal, it will go to 2G (GPRS).

This is normal behavior.

Then, when the phone enters an area with strong 3G signal, it will go back to 3G.

This is also normal behavior.

Except, the restored 3G connection is weak. The icon shows with "no signal bar". It is connected to 3G though.

And it will stay like this until I recycle the connection by going to airplane mode and turn-off airplane mode.

My device is Nexus 6, international model. I installed Android 6.0 by flashing the image.

It is not rooted though and it doesn't have much apps.

And yes, I can reproduce this issue every time, as I know exactly the weak 3G area in our building.

Thanks.

force phone to switch to gsm when lte signal is weak?

as the title suggests is there anyway this is possible? i have the network mode set to lte/wcdma/gsm auto connect but the issue is that i live in an area with low lte coverage and the phone will not switch to gsm mode even when the lte signal is close to none which causes sms not to be delivered and i don't recieve phone calls and it causes a huge battery drain on idle when i go to sleep and wake up with the phone even off sometimes..the issue is gone when i switch to gsm only but it is a pain to constantly go back and forth between switching networks any suggestions?