hello, friend!
Have a nice day!
The version for 6.3.1 does not support add a network adapter, if you need to use that network adapter need be re-install the OS. but suggest upgrading 6.5.1, it is supported that. here is the document link:
FusionSphere Virtualization Suite Product Documentation
https://support.huawei.com/hedex/hdx.do?docid=EDOC1100092089&id=EN-US_TOPIC_0173647512&text=Adding%2520a%2520Physical%2520NIC&lang=en
Hope this helps!