How many PCIe interfaces available in Xilinx FPGA？

Hello， Now I need to build a little AI network using intel‘s FPGA as interconnect chip， I found Xilinx's Ultrascale plus could support at most 4 PCIe gen4， but I need more PCIe interface，I tried to generate 8 Pcie EPs，even X4 is OK，but vivado tell me I could not use more than 4 PCIe interfaces， even with less lane。 Anyone could give me some suggestions tosolve this problem？