I have a Zen G.Fast 300/50 line going into a MT992 modem which in turn goes into a pfSense router. Randomly I'm seeing my G.Fast line drop from 300Mbps down and 48Mbps up to just 100 down and 2-3 up.
To diagnose I've setup BQM and also run a Speedtest every 5 mins and log the result in Zabbix (network monitoring tool). This is what I get:
BQM:
https://i.imgur.com/93EV0YC.png
Speedtest - Bandwidth:
https://i.imgur.com/PkQ4aQT.png
Speedtest - Jitter/Latency:
https://i.imgur.com/WJxMAEI.png
You can see the status with the pfSense box on the left and the ISP provided Fritzbox 7530 on the right in BQM.
Does the above look okay for a G.Fast line and are the random slowdowns acceptable?
I've contacted Zen but everytime we do a test and I plug their provided Fritzbox router the issue disappears but returns after 30 mins.