Context:

Setting up an HCP Gateway and updating settings.

Issue:

When trying to save Gateway settings following message is displayed: Hostname is not a valid hostname!

Resolution:

This may occur if trying to record a gateway hostname starting with digits and not letters. HCP sticks with initial RFC rules for hostnames as detailed below.

• The Internet standards (Requests for Comments) for protocols specify that labels may contain only the ASCII letters a through z (in a case-insensitive manner), the digits 0 through 9, and the hyphen-minus character ('-'). The original specification of hostnames in RFC 952 disallowed labels from starting with a digit or with a hyphen character, and could not end with a hyphen. However, a subsequent specification (RFC 1123) permitted hostname labels to start with digits. No other symbols, punctuation characters, or white space are permitted.

Ref: https://en.wikipedia.org/wiki/Hostname