In the release notes under “problems and limitations corrected” it states that "Improvements have been made to system throughput when NAT is enabled on the SM."
I ran in-house controlled tests and I see roughly half the throughput while NAT is enabled. This is right on par with our previous results while NAT is on.
What exactly did Cambium improve?
The engineers made several improvements to NAT performance to help optimize it. Memory access and NAT queue depth were both improved, resulting in about 4-5 Mbps improvement from R12.0.2 to R12.0.3.1 (when throughput is measured from AP to a single SM).
Using NAT takes additional resources from the (already limited) processor in the subscriber module, and we understand there are still some performance limitations when using this feature, but we are still investigating further improvements.