The Things Network V3 is a public instance running on The Things Stack V3.
The DNS name of The Things Network V3 (EU cluster) is eu1.cloud.thethings.network.
Other Community Clusters use a different prefix.
The URL for the TTN V3 Console (EU cluster) is https://eu1.cloud.thethings.network/console.
When reading The Things Stack documentation be aware that DNS names and URLs mentioned in the documentation (e.g. <tenant-id>.eu1.cloud.thethings.industries) can be different from those used for The Things Network V3.
If you find an issue in the Things Stack V3 documentation then please report the issue in The Things Stack documentation repository on Github so that it can be fixed.
Documentation
Be aware that the documentation for migrating from TTN V2 to V3 is not all completed yet. Some essential information may still be missing.
If you want a smooth migration without running into any issues related to lacks in the documentation then it may be better to wait until all documentation is available and has been completed. For other users this may be less an issue.