hog 4 pc fixturenet ip

Did you try to change it in the settings of your PC.
HOGPC only controls the settings of your PC.

You might configure one network port (e.g. wifi) for hognet and if available another one for fixture net (e.g. ethernet)

I have tried everything. I have downgrade my on pc and it works again :)

Whether or not the fixtureNet IP address is 127.0.0.1 or not is usually determined by the connect state of the adapter. Are you connecting that network adapter on your PC to another computer or switch? It sounds to me that the connection may not be stable or perhaps there is a duplicate IP address on the network.