I tried two more DAC cables and one AOC cable, as support suggested with no luck.

Is there any particular reason why it's locked? https://community.tp-link.com/en/home/forum/topic/742126

I am having the same issue. Hopefully tp link will eventually fix it.

Has anyone had any luck connecting a SFP+ switch to a BE800 via SFP+ DAC cable? It worked with various Ubiquiti and Asus routers.

I switched to different SFP+ DAC cable with same results. I tested with these cables so far: https://www.amazon.pl/dp/B079QT194T?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1...

@Joseph-TP Hi, I wanted to use SFP+ port in 3rd scenario to connect to Hisource 4x2.5G + 2xSFP+ switch to extend number of LAN ports with 10G link, by using DAC cable. This worked with both Asus...