Beryl AX router very slow ethernet connection

I have got a Beryl AX router and it worked as it should until today.
Nothing changed in my network and I had connection speeds up to 400Mbs. Today the max speed I get is around 80Mbs. Beryl is used as access point with Ethernet cable to WAN port.
Checking System log I See that WAN (eth0) is configured as 100Mbs full duplex instead of 1Gbs. LAN is configured as 1000Mbs
I checked all cables but nothing changes.
I also have a GLiNet Opal wich works like it should (transferrates of 400Mbs)
As is the Beryl AX is no good.
Can anyone help?