Dear all, thank you for your support.
Meanwhile I have checked Wifi antenna, but could not find a visible failure. In addition I have flashed latest Android version and realized also here wifi receiption to be poor. So I think it is definetly a hardware issue.

Thank you both for your assistance. Today I realized my phone receives wifi signal if I am very close to my router. So network signals are only identified if they are very strong.
App "wifi scanner" shows significant drop of signal strength even if I move 10m away with no wall inbetween.
Is it possible to be a SW issue? In this case I would like to follow your instruction and reinstall the UT (dev first than stable)

best regards
Bernie

Hi stanwood,
Yes I did, but it doesn't solve the problem. Still the same. Also adding SSID and PW to hidden networks did not help.

Today I installed UT 16.04 on my Nexus 5 and wiped existing Android system, thus there was nothing I would like to transfer.
Everything works fine on my phone except wifi.
Even if I activated wifi it does not show any network. When I run "nmcli r" it shows everything to be active. When I activate Hotspot and connect to my PC this works fine.
But not way to see any wifi network on my phone, even my PC next to the phone shows 20 different networks.
I have no clue where to search or to change things further.
Any help is highly appreciated.

regards
Bernie