Apple airport VERY slow dowload speed

Hi All

I'm setting up a small Ubiquiti wisp style network, running it all off a 200/200 fibre connection.

It's all working well, but I've struck a hitch a one place.

An Apple airport extreme being used as an AP is giving dowload speeds in the order of 5 to 10% of the upload speeds.

If I plug in directly to the live ethernet port of the POE injector (for a Ubiquiti Nanobeam M5) unit I get 60/60 on Speedtest, which is acceptable.

If however I cable connect to either the Airport extreme they have got, or set up an older one I had knocking around, I suddenly get 60ish up but only 5 - 15ish down. I get the same sort of results over the WiFi on either airport too.

Both Airports are in bridge mode, pulling an ip address from an Edgerouter x which is feeding the Rocket M5 at the hub of the network.

I've tried different ethernet cables to the airports and all the other common causes of issues like this.

The fact that I get symmetrical speeds if I connect direct to the POE unit makes me think it is something to do with the Airports themselves, but I can't for the life of me figure out what it might be.

Anyone got any ideas??

**yes I know airports aren't great as AP's go, but they are better than most ISP provided modem/routers, and yes, I know a Ubiquiti AP etc etc would be aa better solution, but I've got to work with what I've got.**

Cheers

Andrew