Video lags on call

I’m having an issue that sometimes the video lags several seconds behind the realtime. Moreover, this lag builds up. Eg, it starts with 1 second lag but after some minutes, it’s 10 seconds after the realtime (eg you clap in your hands and it’s showing 10 seconds later on the other persons screen)

Here is my setup:

A: Laptop Intel Core i7-8550U - WIN10
B: Odroid XU4q - Ubuntu Mate 16.04

I’m having this lag issue only on the Odroid. So my question: is there anything I can tweak to make this performance faster (eg video quality)? I have already altered some settings in Chromium enabling gpu (#ignore-gpu-blacklist , #enable-gpu-rasterization, #enable-sero-copy) but this does not make much of a difference. Some settings stay disabled (url: chrome://gpu)

Moreover, I see some settings not available, mostly WebRTC video hw en/decoding:
(talk uses webRTC) (url: chrome://flags)

Could this be the main cause (I’m getting high CPU usage when performing a call)

have you setup your own (co)turn-server?

Yes I’ve did. I’ve installed coturn on ubuntu 16.04 (= the same server on which Nextcloud is installed on)

Here is my turnserver.conf

listening-port=3478
lt-cred-mech
use-auth-secret
static-auth-secret=
realm=cloud.company.com
total-quota=100
bps-capacity=0
stale-nonce
log-file=/var/log/turn.log
no-loopback-peers
no-multicast-peers
server-name=cloud.company.com
fingerprint
min-port=59000
max-port=59100