Hi
Is ist possible to use 2.5G sfp+ in the router?
If yes: does anyone know wich modules are working?
Thanks
Thomas
I haven’t found a single seller who guarantees that their 2.5G SFP+ modules will work with all Mikrotik products. In some cases, I read customer reviews complaining that it won’t work even that the sellers offered these modules “for Mikrotik”. I contacted some sellers because I’m interested, too, but some didn’t reply and at least one responded that I should buy a 10G SFP+ module for Mikrotik instead.
But there was also one review from December 2022 in which a Canadian customer wrote that he had a “negotiated link speed of 2.5Gbps in CRS326-24G-2S+IN”. Guess it depends on the firmware installed if you’re lucky.
There are a few different articles on STH which test 2.5Gbps compatibility with SFP+ modules…
(although they focus on module speed, rather than module in specific switch compatibility… but it’s a starting point…)
https://www.servethehome.com/sfp-to-10gbase-t-adapter-module-buyers-guide/
https://www.servethehome.com/fs-sfp-10g-t-review-another-sfp-to-10gbase-t-option/
Also, look at: https://help.mikrotik.com/docs/display/ROS/Peripherals#Peripherals-SFP+modules
R
The S+RJ10 will do everything from 10M up to 10G, 2.5G included. The machine I’m typing this on connects at 2.5G to one in a CRS305.
The switch-chip must also support NBase-T standard. 10GBase-T/SFP+ does not imply 2.5G support. Nbase-T is an later standard.
maybe Nbase-T support is not that far from 10GBase-T
at the end 2.5g ang 5g are almost the same thing as 10gBaseT running at lower frequency
Is true that many 10G baseT devices are incompatible with 2.5g or 5g BaseT, specially those on the early ages of 10G base T
Compatibility guide gives us some ligth about the subject
https://wiki.mikrotik.com/wiki/MikroTik_wired_interface_compatibility#SFP+/SFP28_interface_compatibility_with_2.5G_transceivers
Of course you have better chance with MikroTik transceivers specially in this tricky case
Be aware this modules can be HOT
Same issue. I have a crs305 with 2 10gb connections to my IMAC and Synology. Trying to connect 2.5gb Windows machine and the crs305 sees it for a while, but then drops it. The PC does not recognize the network/connection at all. The questions are.
Do I need a specific SFP+ to" RJ45 connector?
Special setting for the network interface on the PC?
Setting on the CRS305 at the port level?
I someone who has done this can give me with settings/hardware it would be appreciated.
Bingo|||| Thanks
Works for me with an S+RJ10 in the CRS305 and an Intel I225-V (Win10 Pro) at the other end. No specific setting needed at either end; they simply autonegotiate to 2.5G.
Using the S+RJ10 to a POE injector to feed my Wireless Access Point at 2.5G.
Might be worth adding what routers/switch’s you are looking at, im a but transient on the form so most of the time I wont see replies but if i know what switch/routers you were looking at connecting at 2.5
I would of been happy to test it out for you 
Might also be worth contacting your local distributor as they might be able to assist testing this for you as well.
S+RJ10 running in CRS326-24G-2S+IN with C53UiG+5HPaxD2HPaxD partner
/interface/ethernet/monitor sfp-sfpplus1 once without-paging
name: sfp-sfpplus1
status: link-ok
auto-negotiation: done
rate: 2.5Gbps
full-duplex: yes
tx-flow-control: no
rx-flow-control: no
advertising: 10M-half,10M-full,100M-half,100M-full,1000M-half,1000M-full,10000M-full,2500M-full,5000M-full
link-partner-advertising: 10M-half,10M-full,100M-half,100M-full,1000M-half,1000M-full,2500M-full
sfp-module-present: yes
sfp-rx-loss: no
sfp-tx-fault: no
sfp-type: SFP/SFP+/SFP28
sfp-connector-type: RJ45
sfp-link-length-copper-active-om4: 1m
sfp-vendor-name: MikroTik
sfp-vendor-part-number: S+RJ10
sfp-vendor-revision: 2.16
sfp-vendor-serial: F0600396D91C
sfp-manufacturing-date: 22-02-15
sfp-temperature: 81C
sfp-supply-voltage: 3.318V
sfp-tx-bias-current: 0mA
eeprom-checksum: good
eeprom: 0000: 03 04 22 00 00 00 00 00 08 00 00 06 67 00 00 00 .."..... ....g...
0010: 00 00 01 00 4d 69 6b 72 6f 54 69 6b 20 20 20 20 ....Mikr oTik
0020: 20 20 20 20 00 00 40 20 53 2b 52 4a 31 30 20 20 ..@ S+RJ10
0030: 20 20 20 20 20 20 20 20 32 2e 31 36 05 00 00 b0 2.16....
0040: 02 1a 00 00 46 30 36 30 30 33 39 36 44 39 31 43 ....F060 0396D91C
0050: 20 20 20 20 32 32 30 32 31 35 20 20 68 00 06 15 2202 15 h...
0060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ........ ........
*
0080: 78 00 d8 00 64 00 00 00 8c a0 55 f0 88 b8 75 30 x...d... ..U...u0
0090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ........ ........
*
00d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0a ........ ........
00e0: 51 00 81 9c 00 00 00 00 00 00 00 00 00 00 00 00 Q....... ........
00f0: 00 00 00 00 00 00 02 00 ec 04 d1 e1 34 2a 0f 00 ........ ....4*..