proper way to limit SFP modules to 1Gb

[DEC740airp414user]

December I upgraded to a DEC740 with 2 of the opnsense store modules labeled DECSFPP10GETH

on my UI switch I just changed it to 1Gb and the light went off the switch and I lost network activity.   had to fix that, power cycling all equipment after this changed did not fix this issue.

under opnsense > interfaces > SPF1lan (what its named) speed and duplex is set to (default)auto.  which I thought would have worked?
1gb lists is there documentation on what I should choose?  using a cat 6 cable
SX
LX
CX
KX

to go to 1gb.   what would you do/ choose?

[pfry]

SX and LX are short and long-wave optics, respectively. CX is STP, KX is PCB (base signaling, e.g. SFP). Most appropriate of those choices would probably be KX. Note the "most" - it may not be appropriate/functional. You seem to have connectivity (at default settings? 10GBASE-T?)... The module has moderate (advertised) power consumption - 1.8W. If it works, you may be stuck with it.

[DEC740airp414user]

both modules are very hot to the touch. I was wanting to limit to 1Gb to see if it helped