Can the global address of the NAT server be an interface address?
Device model: NE20E-S
For the devices upgraded to a version later than V800R008C10, the interface IP address must be able to map a port number.
In the view of the NAT instance named cpe1, use TCP on the internal NAT server to reuse the IP address of GigabitEthernet 0/1/1.
[~HUAWEI] nat instance cpe1 id 1
[*HUAWEI-nat-instance-cpe1] nat server protocol tcp global unnumbered interface GigabitEthernet 0/1/1 11 inside 10.10.1.1 13