TSE & PHY configuration problem

Hello there,

I have an issue of using TSE on Arria 10 SoC board. I build the Ethernet system with internal loopback and all processes seem correct and perfectly work. my issue is that connection works properly only between the FPGA and (PC or Switch). which means I can transmit and receive packets correctly.

But with the same configuration, when I connect one port of FPGA number 1, with one port of FPGA number 2. Ethernet LEDs of both FPGAs are not working and I can't transmit or receive any packets both sides. no response is found(not detected) and all PHY chip LEDs are off.

any helps or suggestions would be highly appreciated.