I have the ER5120 with 2 VDSL 50mbit lines connected. The last few days I had speed issues which I though were due increased traffic. Today I costacted support of bith ISPs because I had download speeds of max 5mbit.

Both lines handshake at 37-41Mbit. When I removed the cables from the modems and stopped using bridge mode both lines had an increase of download speed to 33-37Mbit.

All these seem to be a problem with the ER5120. How can I troubleshoot this issue?

I restarted ER5120 mutiple times with no change. CPU ultilisation was about 20%