The document mentions that the switch is running version 16.12.3 and suggests upgrading to the latest stable code, which is 17.6.4. This version is specifically recommended to avoid known issues in the current version. The provided link also points to the 17.6.4 release for download. Therefore, 17.6.4 is the software version principally discussed in these documents.
The discussed documents suggest upgrading to software version 17.6.4 to resolve connectivity issues.