Microsoft are trying to reduce the amount of settings that are set to default during updates and new builds, however some still occur.
you could set the fixed ip with a command line which you could put into a .bat file and run it with a double click when you experience a problem (or run it on startup)
get some info first
open an elevated command prompt (right click on start and select command prompt (admin)
type the following and press enter
netsh interface show interface
make a note of the interface name
create a new text file with the following
netsh interface ip set address "interface name" static 192.168.0.3 255.255.255.0 192.168.0.1
and save it with a .bat extension
interface name is the name you noted earlier, 192.168.0.3 is the ip address, 255.255.255.0 is the subnet mask and 192.168.0.1 is the default gateway.
right click on the saved file and select create shortcut
put the shortcut on the desktop and right click on it and select properties
on the shortcut tab click advanced
tick the box to run as administrator
click OK and click OK
do come back if you experience any problems.