The latest Windows operating system available for the Lumia 735 is Windows 10 Mobile version 1703, build 15063.909.
I have Windows 10 Mobile version 1607, build 10.0.14393.2068 on my Lumia 735 now.
If I try to run "Phone update", I get the message "Your device is up to date" :(
While my phone can't find update?