LTE signal is not received by my HTC One M8

[Reuven18]

Hi
I bought my HTC One M8 as a new one in Aliexpress - instead of crashi Galaxy S5.
It come with stock Android 6 + Sense 7;
I rooted it and flashed Nougat. Great. After I insert a nano SIM (In my S5 it was micro SIM), I discovered that LTE signal of my provider is not appearing.
IMEI was checked:
It is regular M8 device with LTE abilities to receive 1800+, like in my region:
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M8#UHL-C9
SKU,HTC,Traditional Chinese,HKG,Bootloader Lock,Rose Gold,w/o SIM Lock,M8#UHL-C9#ASIA
-----------------------------
All settings were done - "LTE preferable" in "Cellular Networks", "LTE/UMTS" by "*#*#4636#*#*" etc.
Network metering applications say there is no LTE signal received by device...
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The point is that I did not check LTE with original ROM inside (still had not nano-SIM that time)
May be this is a problem of ROM? Or LTE Radio?
How can I check it?
Is it possible to downgrade to original 4.4.1 by ADB?

Thank a lot!

 

[B. Diddy]

I moved this from the Google Play Edition M8 forum (not sure why it was there -- it doesn't sound like you have the Google Play Edition) to the M8 Rooting/ROMs forum, for more specific traffic.