I just bought a pair of CPE210 V3.20 to use as a AP/Client pair to connect a separate garage, ~200' away. Both devices have been updated to 

2.2.6 Build 20230907 Rel. 39920 (5553)

I'm currently testing them at home, with the devices only a few feet away and pointing towards each other. I have a main router connected to the AP CPE210, and another router configured as AP/switch connected to the CPE210 client. 2 ports on the switch are on main lan, one on vlan 101, one on vlan 102. The CPE210 are configured as 802.11n only, 20/40MHz bandwidth, Max TX rate 15, no MAXtream

I'm using a Raspberry PI 3B+ with an iperf3 server to measure the network speed, connected to the AP/switch router. On the two main lan ports, I get speeds of around 82 Mbits/sec, which is as good as I expected conidering the 100MBits/sec ethernet and communication overhead. The weird thing is that, when I connect the RPi 3 to vlan 101 or 102, speed drops to 52 MBits/sec, which is way more than expected.

For reference, with the two routers connected directly (no CPE210), the speeds are, respectively, 94 and 89 MBits/sec, so the vlan slows the system down by around 5 MBits/sec. But the CPE210 vlan seems to add another 25 MBits/sec loss on top of it, which seems entirely unreasonable.vlan tags only add 4 bytes to the packet, so should not

Is there a way to minimize the data rate loss due to the vlan?