Hello, i'm new here so forgive me if i ask something silly.
Short introduction : i have a 400/40mbit ISP, i have my old WR1043ND V2 with stock latest firmware, with hardware NAT enabled it works fine at 400/40mbit speeds, no problem whatsoever. i use CAT6 LAN Cables, Gigabit Router + Adapters.
Recently i got the WR1043ND V4 and the stock firmware was horrible, with Hardware NAT enabled (or NAT Boost they call it now) i could only reach a max download of 100 - 150mbit. with Software NAT it reached a max download of 250mbit. at first i thought my product was defective so i RMA it back to the store and i got a replacement, only to find out it suffers from the exact same problem.
So i upgraded to this LEDE firmware and it works fine, but still i get max 250mbit so i assume this LEDE firmware does not support hardware NAT? i tried looking for a package to install but couldn't find anything. hope there is a solution for this.
For now i will put my old V2 router back because this one works fine.
LEDE (and Openwrt) doesn't support Hardware NAT. But you can build your own firmware with Qualcomm Fastpath for LEDE tweak, it can easily reach 400mbps for downstream with your router hardware.
I have old router ar7161 chipset, with Fastpath can reach ~550mbps NAT down/up.
it has been discussed about this, this is a software hack, real hardware nat would be in the switch driver
this is the patch for trunk, if you want to build your own image (on my v3 it does ~900+mb/s) https://github.com/lede-project/source/pull/1269