Dear Community,

maybe I'm overlooking something that can be fixed easily. I'm currently running a setup between two switches that goes like this:

TP-Link T2600G-52TS <> Lantech mini GBIC <> Fibre line <> Lantech mini GBIC <> Linksys SRW2024

This setup has been running for quite a while successfuly and still does. However I wanted to exchange the old Linksys switch for a new TP-Link switch. So I arranged the following setup:

TP-Link T2600G-52TS <> TP-Link TL-SM5110-SR <> Fibre line <> TP-Link TL-SM5110-SR <> TP-Link TL-SG3428X

So now there is TP-Link in place exclusively. What puzzles me now is that I cannot get a link on the fibre line on either side of the switches. The according LEDs remain silent.

Since the TL-SM5110-SR is a 10G (SFP+) capable model whereas the T2600G-52TS is only a 1G (SFP) capable model I had to dim the speed of the fibre interface to 1000M on the TL-SG3428X. After having synchronised the speeds of the fibre interfaces to 1000M on both sides the LEDs on the TL-SG3428X went on showing orange = link up = 1G = 1000M. But the according LEDs on the T2600G-52TS are still silent and the link is shown as "down" on the web GUI.

I tried rebooting both switches to no avail. As well I tried interchanging the old and the new mini GBICs unsuccessfully but I can say that the TL-SM5110-SR mini GBICs seem to run in the old setup properly.

So the question is: Is there anything I'm obviously missing? Do I have to configure the ports on the switches in some special way that is not the default setting?

Thank you very much in advance, any help is appreciated :-)