HEX S (2025) sfp datarate issue

RouterOS General
1

Hi everyone,

I’m experiencing an issue with a 2.5GbE SFP module in my MikroTik hEX S (2025). The module uses a Realtek chip and I’m seeing some strange behavior in terms of throughput:

  • Download: Achieves over 1gbps, as expected for a 2.5GbE module.
  • Upload: Capped at 100mbps, which is significantly lower than expected.

I’ve tested multiple cables to rule out any cable-related issues but the problem persists across all tests. My suspicion is that the Realtek chip in the SFP module may not be fully supported by RouterOS?And thats what is leading to this upload speed limitation?

Has anyone else encountered similar behavior with a Realtek-based 2.5GbE SFP module on the hEX S or other MikroTik devices? If so, do you have any insights or workarounds? Additionally, does anyone know if/when MikroTik plans to add support for this chipset in RouterOS?

Any information or experiences you can share would be greatly appreciated!

Thanks
Thomas

2

There’s a general problem with performance of ether1 (on hEX refresh and hEX S 2025) and SFP+ (on hEX S 2025) due to how these ports are internally handled (directly by CPU unlike other ports which are handled by switch chip). Search the forum, you’ll find the relevant thread (it started with ether1 issues on hEX refresh) it applies to your case as well.

3

It was even commented 1h ago: Hex refresh download speed - #29 by Hiutale

4

I don’t own either of the devices but saw multiple threads about this. However, at least some report it’s working fine: https://www.reddit.com/r/mikrotik/comments/1ldf4rj/hex_s_2025_e60iugs_simple_25g_nat_throughput_test/

5

Did you use auto-nego on that module?

RTL8221B is known to use rollball protocol, and in my experience, I have had no problems with manual nego for 2.5G link.

When set to auto-nego, it behaved very strangely, such as not being recognized or link flapping.

And some modules use Motorcomm YT8821, and this chipset has had problems with asymmetric speeds.

(Some sellers advertise the module chipset as Realtek, but it may actually be Motorcomm chipset.)

6

If anyone is interested, the fix for these issues just dropped in 7.20beta5

7

Tested on Hex Refresh but I assume for Hex S it will be the same.

8

What are your findings? Is it fixed?

9

For Hex Refresh, yes.
Definitely a lot better then how it was before.

10

Did someone also try the new HexS with latest 7.20beta 5 ? I´m planning to buy some HexS. It would be reassuring to know if the problems are gone.

11

Okay so I've been testing for my specific use case for a while, an update did improve this situation massively by taking the upload up to around 600mbps from 100mbps. Doing further testing I was able to achive the full 1gbps both ways by changing the queue type on the WAN port(ether 5). Switching from the hardware queue to FQ-CoDel eliminated the problems I was experiencing.

Interestingly, during this process, I encountered a separate issue where the SFP module would silently lose connection. This was resolved with a beta firmware update that adjusted the module's clock speed(if I understood the patch notes correctly).

For anyone stumbling upon this thread with a 1Gbps PPPoE connection, the MikroTik hEX (2025) can handle it effectively with the following setup:

My setup

  • Ether5: WAN (Queue type set to FQ-CoDel)
  • SFP: LAN
  • Firmware: >19.4

Hopefully this can be of use to someone.