Hello folks,

So I'm having really slow download speeds with the ER8411 when using TP Link SFP+ TL-SM5310-T. For reference, the same happened with a Wiitek module as well. Here some details: 

ER8411 FW 1.1.0

SFP+ Module TL-SM5310-T 

Standalone 

Configuration: 

ISP Modem on Bridge (2.5g port) -----> ER8411 (SFP+) ----> PCs and Access points in the switch ports. 

Here the tests I've made: 

1)  Iperf from PC1 to PC2, on standard ports. Get full gigabit speed. Nothing wrong with the switch. 

2) iperf from PC1 to PC2, one in standard port and the other on SFP+ port 2 Lan, with the SM5310-T. Get full gigabit speed. Module and SFP+ port 2 working perfectly. 

3) ISP Modem, Bridge mode, connected to standard Wan port 4, PC1 connected to ER8411. Get full gigabit from ISP. So it doesn't seem to be anything with the ISP. 

4) ISP modem, Bridge mode, connected to SFP+ Port 1 with the module, PC1 connected to ER8411. Speed is throttled down to 200 - 300 mbps. 

So the only variable that I could see is the use of the SFP+ port as the iperf and other tests show the module and configuration are all working. 

I've tried both Flow Control enable and disabled; Both in the WAN SFP+ Port 1 and Switch ports. Nothing seems to resolve this issue. 

I know there's been some issues in the past related to this, but that was supposed to be fixed in the 1.0.2 fw.