I am not sure what "gui81-alfresco1" is supposed to be. Is it the name of the Docker container or the image? If it is an image, who provided / built it (using what base)?
Generally I would assume that by restarting your Docker instance, the alfresco-global.properties simply resets to the default state of the image. This would happen e.g. if you used the default Alfresco Docker images and completely stopped + removed a running container instance, and then restarted. In the default images, this is by design, and you are supposed to provide custom parameters via environment variables passed to the Docker container, typically using the JAVA_OPTS parameter with addition of various -D Java system properties flags.
Also, it is generally not recommended to use IP-based addresses for complex functionality like editing in MS Office. Windows / Office have various security mechanisms in place which typically expect / require a proper FQDN to be present, otherwise they can potentially limit some functionalities for security reasons. As such, you should try to give your Alfresco instance a proper domain name entry, e.g. alfresco.acme.com, and better yet, set up a proper reverse proxy with SSL termination, so Windows / Office may even support potentially insecure authentication methods, like HTTP BASIC.