Hi guys

I got a Mikrotik router and a QNAP NAs

Nas has 1 SFP+ 10Gb port that works fine with Mikrotik SFP port and I wanted to add additional 1Gb copper link as a backup link

Obviously It has to be some sort of STP configuration

I set:
Past cost 5 for SFP
Past cost 10 for Copper

Unfortunately, they remain designated ports and router freezes soon after that
in logs:
sfp-sfpplus1: bridge port received packet with own address as source address (c4:ad:34:f6:08:25), probably loop


Can somebody please advise?

Thanks a lot