Why does the mini pcie wifi adapter not work?

Question

Do it yourself

I don’t even know how best to formulate the essence of the question for the title. The problem is the following - there is a device with ubuntu on board, it has one mini pci-e connector. A mini pci-e HD decoder (bcm70015) and a wifi adapter (intel 7260 HMW) were purchased. Both work fine on the device, but there is only one connector, so I bought one, and then the second splitters for mini pcie (pcie bridge) - one on PEX8603 and the other on PI7C9X2G304SL. Then the problem surfaced, the HD decoder only works with PI7C9X2G304SL, and the wifi adapter only with PEX8603, and if you insert a decoder and another splitter into one splitter, and insert a wifi card into the second splitter, then everything works!). But this is a crutch, you need to do it right. I've already broken my head, I can not understand what's wrong.