I have a Banana PI R2. I’m testing its NAT speed between two computers that are a few feet apart. For data coming in the wan port and going to the LAN port, I’m getting about 35MiB/s. Going the other way, I get 92MiB/s. I know it’s the router’s fault, because I ran the same test with an EspressoBin and got 92MiB/s both directions. Although the EspressoBin is unstable and has unexpected reboots.
I ran a ping test, and there weren’t any dropped packets.
I’ve tried two different images. I built an OpenWRT from the source at https://github.com/eliasmagn/bpir2wrt. The other image I tried was frank-w’s Debian image at https://drive.google.com/drive/folders/1oP7jy1KrrIOifvImo2nQ59wx3_9hHkgk with the 4.14 kernel. I tried turning on hwnat, but it didn’t help.
I tried the official OpenWRT image too. It booted up, but I couldn’t get it to install enough packages to setup the nat. It was trying to pull the packages from the mainstream OpenWRT, and the versions didn’t match.