I've just installed an T2600G-28SQ sfp switch and sfp's, using 80km 1490/1550 sfp's from fs.com. They claim that these are compatible with the TP-link switches. Everything looks fine -- links come up (mulitple ports), but I can never get any data across the link. The other end of each link is a media converter. I've tried ping from the switch to the device on the other end of the media converter, no luck. If I use the same sfp's in two media converters, all works perfectly. I can also ping the rest of the network (connected via copper) from the switch, and the copper ports work fine.
I upgrade the firmware to the latest version, but no difference.
Any help / ideas would be hugely appreciated!