I'm back on it...The connection is stable but performance is poor when clients connect via WiFi or mobile connection. Now I understand the problem with mobile connection but WiFi used for testing is OK -> 10Mbps Downstream / 6Mbps Upstream, very stable, no other clients connected to the WiFi. The server side connection is 60Mbps / 20Mbps.
The issue is that speed drops to few kb/s when connected via Wifi and copying a folder containing e.g. 200 small files (101MB total) which I find strange. Another example is launching a software that relies on data stored on a shared drive - it gets painfully slow as it needs to load data from many smaller files.
Iperf test on that connection:
local 192.168.2.1 port 5001 connected with 10.8.0.6 port 50079
[ 4] 0.0-12.4 sec 8.66 MBytes 5.85 Mbits/sec
All seems to be good for large files - no problems, the speed is what you expect. Transferring smaller files is a completely different story - it just gets very slow.
This is sample config I'm using:
I have also created QoS rule for 1194 ports inbound and outbound but that did not help.
Suggestions to the problem would be very welcome.