please have a look at Call for info: Unknown OS and Service Banner Reporting for ways to identify how the OS was determined and a possible output which could help to improve the detection.
If you’re getting this vulnerability messages this means you’re using either any of the pre-defined
Ultimate scan configs or using an own scan configuration with
safe_checks set to
no. When using those scan configs you need to live with possible false positives if OpenVAS/GVM is trying to stop a service or kill a host as there is no absolutely reliable way to check this.
Please switch back to the highly recommended
Full and Fast scan configuration (without the
Ultimate in the name) to avoid such situations if required.
If you want to keep the current used scan config it is up to you to research and decide if this is a false positive or not and if you want to work with an override as described in Overrides and False Positives.