I tried to use Samsung 960 PRO in adapter and first I was able to access it but when I rebooted it was not recognized at all, meaning it does not show up in lspci, both in OpenWRT and Ubuntu. I checked it in PC and it works flawlessly. I noticed this in dmesg:
[ 3.635071] PCI host bridge /cpn-110-master/pcie@0x600000 ranges:
[ 3.641201] IO 0xf9000000..0xf900ffff -> 0xf9000000
[ 3.646365] MEM 0xf6000000..0xf6efffff -> 0xf6000000
[ 3.652896] armada8k-pcie f2600000.pcie: Link not up after reconfiguration
[ 3.659859] armada8k-pcie f2600000.pcie: PCI host bridge to bus 0000:00
Here is whole dmesg pastebin. I noticed that some other people have this problem, maybe this is related fix? https://patchwork.kernel.org/patch/10146687/