AP Throughput and latency

[flybob]

Hi,

I've tried to make it work but after several weeks i might as well seek help now.

I have a usb 4g modem connected to my Rpi4, as well as a USB NIC.

I use the currently latest OP (Settings 2.3.0).

On the OP computer, i get 7+ Mbit speeds and normal surfing, no issues there. Both 4g and Wifi internet connection works.

Using the onboard wifi as AP, in 2.4Ghz, tried different channels and also what device should be shared.

For all connected clients (Windows laptops, Android phones/pads) the latency is 1000+ms and very poor performance in general.
While doing speedtests on clients the cpu load on the Rpi4 only increases slightly, so not a bottleneck there.
It's impossible to watch videos and connecting going up/down/fast/slow/on/off....

I also tried using the USB NIC as the AP, for testing purposes, but that wont work wither. 
It can connect to the AP but no internet connection is shared.

So I really can't get around to get proper internet shared through the AP on board. Ideas?