8900AX-2400 Hangs with Port Mirroring Enabled

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Hi,

I have recently upgraded from a 7800DX to an 8900AX in order to support a change from ADSL to VDSL.
The 8900AX has been operating fine on ADSL - and post ISP migration fine on VDSL (download 50Mb, upload 10Mb).

I need to enable port mirroring - in order to monitor ingress / egress analysis and intrusion detection.

However when I enable in/out mirroring of ptm0 to P5 port the router consistently hangs < 10 mins.
Definition of hang being wifi networks stop, local routing stops, lights still on - but requires a power recycle to recover.
The issue also occurs when there is no device attached to P5.

Anyone have good or bad experiences with 8900AX port mirroring ?

Best Regards