The only Ethernet hardware products Acorn made were Ethernet interfaces. Ethernet interfaces fall into 3 categories:
Acorn also produced a number of software products that used Ethernet, In particular AUN (Acorn Universal Networking) products such as the Level 4 fileserver (AES50), Intertalk (AES72) and Omniclient (AES75). The Acorn software products are currently out of the scope of Chris's Acorns, athough I may revisit that when I have completed cataloging my hardware.
In addition to Acorn, a number of 3rd parties produced Ethernet interfaces for Acorn computers. The interfaces are documented here and in the Upgrades section of Chris's Acorns.
NetGain is a 'High Speed Application Loader'. NetGain was available for Econet or Ethernet and consisted of a Licence Card podule, end user licence packs and the software on a 3.5" disc. In use it marked reduced loading times. There is a review in Archive Vol.7 Isuue 1 (October 1993) page 77.
Here is the Digital Services NetGain Licence Card and more details of NetGain.