Can I connect a NAS (923+ with 10GbE card) to a switch 10GbE (copper SFP+) Uplink port?

Well, the title says it all.

I’m looking at TP-Link SG3428X switch to buy and connect my DS923+ with 10GbE card to the switch uplink port with copper SFP+, but I’m not sure if it will work as it should.


I can only speak from research, not experience yet, but it should work with an SFP+ to RJ-45 transceiver, e.g. something like this:

(But I’ve read that you shouldn’t populate a switch’s SFP+ ports with too many of those copper transceivers. But plugging in one or a few should be A-OK.)

Generally, 10GbE copper to 10GbE SFP+ should work fine: same speed/bandwidth.

According to what I’ve read, you can in fact use an uplink port on a switch as a regular port. It’s always possible that this needs to be manually set up in the switch’s management software, so I’d research TP-Link’s manuals/forums for more info, but maybe someone here has direct experience with a TP-Link switch. This is supposed to be done with a crossover cable, but I don’t know how this would work with SFP+ and transceivers, so someone else should chime in.

Text below is just tangential.

If you’re attaching an RJ-45 cable with a NIC whose speed is below 10GbE, then you need an auto-negotiating SFP+ to RJ-45 transceiver, which is slightly more expensive than a regular one.

(Someone else needs to answer this, but it might also be possible to set the SFP+ port to a lower speed, e.g. 2.5GbE, if the switch is managed, and then use a regular SFP+ copper transceiver for a 2.5GbE connection.)

N.B.: my router/switch of choice is currently the MikroTik CCR2004-1G-12S+2XS plus a ZyXEL XGS1210-12 (connected via 2 x 10GbE SFP+ aggregated uplink), and I’ll need to use one of the router’s 10GbE SFP+ ports for the 1GbE copper WAN uplink, and I’ve chosen to use an auto-negotiating transceiver. (MikroTik also sells these.)

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According to this answer on ServerFault SFP+ ports handle receive and transmit automatically. However, the discussion is about passive Twinax SFP+ cables, and I can’t say if it works with one end of the cable being an RJ-45 connector. But see this discussion; quote:

I don’t think [I]'ve seen a switch that didn’t have auto MDI/MDI-X capabilities (or it was controllable in software) in about 8 years. You should be able to connect you[r] workstation to an “Uplink” port and it’ll work just fine. You may have to make software configuration adjustments in the switch config, you[r] documentation should tell you if you need to and how to do it.

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