Infiniband adapter down

edit: On CentOS 8.5, tried with Mellanox driver 4.9-4.1.7.0 (legacy) and 5.5-1.0.3.2:

I am not able to get my Infiniband adapter working. The output of ibstat states that it is down:

    CA 'mlx5_0'
        CA type: MT4123
        Number of ports: 1
        Firmware version: 20.31.1014
        Hardware version: 0
        Node GUID: 0xb8cef60300a7fbbc
        System image GUID: 0xb8cef60300a7fbbc
        Port 1:
            State: Down
            Physical state: Disabled
            Rate: 10
            Base lid: 65535
            LMC: 0
            SM lid: 0
            Capability mask: 0x2651e848
            Port GUID: 0xb8cef60300a7fbbc
            Link layer: InfiniBand

And mlxlink -d mlx5_0 outputs:

Operational Info
----------------
State                           : Disable
Physical state                  : ETH_AN_FSM_ENABLE
Speed                           : N/A
Width                           : N/A
FEC                             : N/A
Loopback Mode                   : N/A
Auto Negotiation                : ON

Supported Info
--------------
Enabled Link Speed              : 0x00000075 (HDR,EDR,FDR,QDR,SDR)
Supported Cable Speed           : 0x00000007 (QDR,DDR,SDR)

Troubleshooting Info
--------------------
Status Opcode                   : 1036
Group Opcode                    : MNG FW
Recommendation                  : Connected wrong module type. Change to a different module type.

So here I have a troubleshooting info, I just dont understand it. I am pretty sure the cable is connected, could it be some incompatibilities between Connect-X 3 (where opensm service runs) and Connect-X 6 adapters?

edit:

The adapters are connected by a Mellanox SX6012 switch.

The output of ibcheckstate -v is given in the following. Port 1 is the node with opensm running, the port of the new node with the ConnectX-6 adapter is missing.

# Checking Switch: nodeguid 0x248a070300ccc140
Node check lid 2:  OK 
Port check lid 2 port 1:  OK 
Port check lid 2 port 2:  OK 
Port check lid 2 port 3:  OK 
Port check lid 2 port 4:  OK 
Port check lid 2 port 5:  OK 

# Checking Ca: nodeguid 0x0cc47affff5fb364
Node check lid 4:  OK 
Port check lid 4 port 1:  OK 

# Checking Ca: nodeguid 0x0cc47affff5fb8e4
Node check lid 6:  OK 
Port check lid 6 port 1:  OK 

# Checking Ca: nodeguid 0x0cc47affff5fb4c4
Node check lid 5:  OK 
Port check lid 5 port 1:  OK 

# Checking Ca: nodeguid 0x0cc47affff5fb89c
Node check lid 3:  OK 
Port check lid 3 port 1:  OK 

# Checking Ca: nodeguid 0x248a070300f97f50
Node check lid 1:  OK 
Port check lid 1 port 1:  OK 

*** WARNING ***: this command is deprecated

## Summary: 6 nodes checked, 0 bad nodes found
##          10 ports checked, 0 ports with bad state found

The cable has worked at least with a ConnectX-4 adapter.