Ubuntu – Dell XPS 15 7590 Killer wifi 1650 card not recognized in Ubuntu 19.04

I have a new Dell XPS 15 7590 laptop. It has a Killer 1650 wireless adapter. It didn't work on first install, but after installing the right drivers (with some help from the ppl at Killer Networks), and disabling secure boot, I got it to work. It worked on two different wifi networks. Today I took it to the client's office, but wifi doesn't work now. Ubuntu doesn't seem to see a wireless adapter (but it did until yesterday). The bios on the laptop says it has an intel wireless adapter, I'm not sure if that's the Killer card or not.
I'll replace the Killer card by the card from my old XPS15, but I am curious if I can make the card work. It does seem to me it's a hardware issue, as the card doesn't seem to be shown in the bios properly.

I followed the steps from here to install drivers:
https://support.killernetworking.com/knowledge-base/killer-ax1650-in-debian-ubuntu-16-04/
I did that again this morning.

$ lspci -nnk | grep -iA3 net

    3b:00.0 Network controller [0280]: Intel Corporation Device [8086:2723] (rev 1a)
    Subsystem: Bigfoot Networks, Inc. Device [1a56:1654]
    3c:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. 
    RTS525A PCI Express Card Reader [10ec:525a] (rev 01)
    Subsystem: Dell RTS525A PCI Express Card Reader [1028:0905]
    Kernel driver in use: rtsx_pci

What can I do to make wifi work on my new laptop?

Edit:
Wifi now works. I had some help from the ppl at Killer Networks. They added some info to their support site: before installing the drivers as described, make sure you disable secure boot in the bios.