x230 upgrade, keep losing wifi (internal card, dongle)

I am having incredible trouble with networking. (original post , different forum). I'm upgrading a secondhand Thinkpad x230 (installed: coreboot with SeaBIOS, have run me_cleaner, using Lubuntu Cosmic). Suddenly, internal wifi refuses to work. Stopped inexplicably 3 weeks ago after I reassembled the machine (keyboard, etc). Tried a different motherboard (original config), booted live USBs (Fedora, Manjaro, etc), traced antenna wires and different wifi card (2nd hand). No joy. - Wifi sometimes works with a DWA-131 Dlink "Wireless N Nano USB Adapter", but usually not. - A Huawei 4G modem seems to work perfectly, recognized as a wired ethernet connection. - Not sure, but DWA-131 adapter seems to start working after the 4G modem has been inserted. My last dmsesg dump is here , if that's of any use. (Timestamp is wrong, so clock is out, apparently). The last few hours shows me plugging and unplugging things (including a computer-to-computer ethernet link, below), and the DWA-131 adapter starting to work somehow. Really not sure how to proceed. --- There's another issue I'll post separately: a cable connection from the x230 to a Dell XPS13 prompted a strange network in someone else's name.