MikroTik SFP, SFP+ & SFP28 Compatibility: Why Your Module Won't Link (2026)
One of the most common MikroTik support questions — raised again recently about the CCR2004-1G-2XS-PCIe — is some version of: "I've tried several SFP modules and DAC cables and I can't get a link. Which ones are actually compatible?" The good news is MikroTik gear is largely vendor-neutral, so this is rarely about branding. It's almost always about speed, module type, power/heat, and a couple of RouterOS settings. Here's how to get a link.
1. Match the speed the cage actually supports
SFP28 cages (the "2XS" ports on a CCR2004-1G-2XS-PCIe) run 1G, 10G and 25G. The in-between rates — 2.5G and 5G — are special cases that many MikroTik ports won't auto-negotiate, which is why a 2.5G module often simply won't come up. Worse, a 2.5G XPON module isn't a normal optic at all: XPON/GPON "ONU" SFPs are fiber-to-the-home modems that expect ISP provisioning, not a plain Ethernet link to a switch port. Don't expect one to light up as a 10G/25G uplink. For a straight uplink, use a 1G, 10G or 25G module that matches the port.
2. Copper RJ45 SFP+ (10GBASE-T) is the hard case
Copper 10GBASE-T SFP+ modules draw a lot of power and run hot, and many SFP cages — MikroTik included — don't reliably power third-party 10G copper modules. That's the usual reason a generic 10G copper SFP+ won't link or drops after warming up. For 10G over RJ45, MikroTik's validated S+RJ10 is the safe choice (and still give it airflow). For 1G copper in an SFP cage, use the S-RJ01.
3. DACs: easiest, if the speed matches
Direct-attach copper (DAC) cables are usually the most trouble-free option — but the cable's speed has to match the port, and both ends have to agree. A 10G DAC plugged into a 25G SFP28 cage needs the port forced to 10G (see below), and a passive DAC is speed-coded, so use a 10G-rated DAC for 10G ports and a 25G DAC for 25G ports.
4. The RouterOS settings that fix "no link"
When a module is physically right but still won't come up, it's usually negotiation. In /interface ethernet, don't leave an SFP+/SFP28 port on auto — turn auto-negotiation off and set the port speed to match the module (for example, force 10G for a 10G module or DAC in a 25G cage). Check the interface's monitor/SFP readout too: it reports the module's vendor, supported rates and Tx/Rx light levels, which tells you instantly whether the optic is seen, mis-rated, or getting no signal. Finally, update RouterOS — newer releases regularly add or improve module support.
5. The reliable path: validated optics
MikroTik doesn't lock you to branded optics, but the fastest way to a guaranteed link is to use modules proven in MikroTik gear — they interoperate with standard single-mode/multi-mode fiber on the far end. The common ones:
- S+RJ10 — 10G copper RJ45 (the right way to do 10GBASE-T)
- S-RJ01 — 1G copper RJ45
- S+31DLC10D — 10G single-mode, 10 km LC
- S+85DLC03D — 10G multi-mode, 300 m LC
- XS+31LC10D — 25G single-mode, 10 km LC
- S+DA000x / XS+DA000x — 10G / 25G direct-attach (DAC) cables
Browse the full set on our MikroTik SFP modules & transceivers collection, and for choosing by distance and form factor see our guide to choosing MikroTik SFP modules. Sorting out optics for a specific router like the CCR2004-1G-2XS-PCIe? We're an authorized MikroTik reseller with competitive pricing and fast US shipping — ask us for a matched set.
Frequently asked questions
Why won't my 2.5G SFP module link in a MikroTik SFP+/SFP28 port?
Because the port may not negotiate 2.5G — those cages are built around 1G/10G/25G. Force the port speed in RouterOS, and if it's a 2.5G XPON/GPON module, note that those are ISP ONU devices that need provisioning, not a plain Ethernet uplink.
Do copper 10GBASE-T SFP+ modules work in MikroTik?
They're hit-or-miss: 10G copper SFP+ modules draw high power and run hot, and many cages won't reliably power third-party ones. Use MikroTik's S+RJ10 for 10G copper and keep it ventilated.
Does MikroTik only accept its own branded optics?
No — there's no vendor lock. Third-party optics work as long as the speed and type match the port, but MikroTik-validated modules are the safest way to a guaranteed link.
How do I force a MikroTik SFP port to a specific speed?
In /interface ethernet, disable auto-negotiation on the SFP port and set the speed to match your module or DAC (for example 10G). Then check the interface's SFP monitor to confirm the module is detected and receiving light.