I am trying to connect the FPGA with a QSFP Range Extender from 10Gtek https://downloader.vip/rightmove/(CVT-OEO-Q/4S1C)
... basically the QSFP port from the FPGA goes into the range extender and the SFP ports from the extender can be collected at the destination.
In this setup I am seeing very inconsistent results
Only thing I would infer from all this is that the GTH Transceiver is not configured properly for this device.
Please help with this issue
Have you tried using the Transceiver Toolkit to tune the analogue properties of the link? If it starts/stops working over time, I'd think you probably have a thermal problem and your links are tuned too close to the edge of the eye (so will start to have issues as thing heat up / cool down).
Hope that helps.