My understanding of these routers is that the gigabit switch is independent from the router. They're physically on the same board but the router is just another machine on the switch. If the switch table says portA->portB it doesn't matter what the router on portC has decided to offload or not.
Edit: Maybe you mean Wifi to wired may have a disabled offload? That path does go through the router and not directly through the switch. For bigger installations I end up having one of these with wifi disabled as the router (firewall, dhcp, etc) and individual ones connected through ethernet as dumb access points (same SSID on all and straight bridge from Wifi to Ethernet). That should also avoid any issues and is a good setup to get more wifi coverage with a simple config.
Good to know, would explain why there's a phantom eth port on some of these routers, must be used to connect between router and switch chips. Sounds like you're right about wifi->wired transit though if this is the casr
The typical architecture for routers these days is that the main SoC has two ethernet interfaces, each of which is connected to a 7+ port managed switch. One of the host CPU's interfaces is on the WAN VLAN, and the other is on the LAN VLAN. Some older routers used to have just one ethernet link between the switch and the CPU, with the CPU's other interface exposed directly as the WAN port. That made it easier to avoid bloat or bugs in the ethernet switch itself, but was fundamentally incompatible with the NAT offload those switches provide, so that configuration is now almost impossible to find.
This also makes these little routers extremely powerful. Since those switches have VLANs as well you can create very interesting topologies that would require much more expensive managed switches to achieve. I run an extra VLAN from my router, to one of my APs, to a dedicated wifi SSID to another wireless router to ethernet to a TV box so I can have the TV signal in a place I can't run ethernet to. Doing it through the normal Wifi would be a bad idea because the provider uses multicast IPTV and if you put that on your wifi every connected devices receives it. And this is all done with 3 50€ routers running LEDE, each with different VLANs and wifi SSIDs configured. They make for a really flexible setup.
Edit: Maybe you mean Wifi to wired may have a disabled offload? That path does go through the router and not directly through the switch. For bigger installations I end up having one of these with wifi disabled as the router (firewall, dhcp, etc) and individual ones connected through ethernet as dumb access points (same SSID on all and straight bridge from Wifi to Ethernet). That should also avoid any issues and is a good setup to get more wifi coverage with a simple config.