Low LAN and 5GHz WIFI speeds from RAXE500 Router?

For the RAXE500, there are no LAN side internal bottlenecks. Basically more than enough PCIe throughput between the WiFi radios. The 5 gigabit Ethernet ports have dedicated hardware acceleration handled by the SOC the 1 2.5GbE port is also directly handled with hardware acceleration by the SOC, and uses a front end Ethernet transciever for the port. (main reason why even if you saturate the ports with traffic (if netgear armor is not in use), the CPU remains largely idle.

From tests that I have done, I was unable to saturate them in a way that would expose an internal bottleneck.

For WiFi, each radio essentially has a PCIe connection back to the SOC, and at least with 802.11ax the PCIe 2.0 connections are unlikely to be a bottleneck.

In terms of WAN to LAN performance, for a single gigabit Ethernet client, it can sustain 940Mbps without issue, and a single 802.11ax client at 160MHz channel width and 2 stream WiFi, can maintain around 1.8-1.8Gbps. And if using multiple clients such as 1 wired and 1 wireless downloading from a server connected to the WAN port when set to the 2.5GbE port, then sustained speeds for a TCP connection are 2380Mbps for upload and download, and for simultaneous upload and download, speeds up to 4016Mbps (simultaneous upload and download, fully saturating the port) are possible.

If Armor is active (activates by default if using the app to set it up if within the trial period), then speeds will be lower and more variable depending on the type of traffic and how much work it has to do to inspect the contents.