I am using Ubuntu 18.04 on an Asus laptop. The internal wifi does not recognize 5GHz channel so I purchased a TP-Link T9UH. I followed the first half of the answer found here How to compile TP-Link T9UH Wireless Driver without Internet Access? I'm running into issues (did not install dkms yet) and now the USB wifi seems to be working. My wifi settings show both wifi connections now and the new one sees and connects to 5GHz channel.
But using the GNOME wifi manager, it does not seem possible to turn off just 1 wifi connection. If you do, what it really does is just turn on Airplane mode which turns them both off.
Is there a way to manage the 2 wifi connections independently? Is command line the only option here? Thank you
EDIT2: I suppose ifconfig wlp3s0 down (or up) is the easiest way to do this and it does seem to work. however it bugs me that Network Manager still shows that the internal adapter is connected. maybe i misunderstand something? but it seems to me that I am not the first person wanting to do this so I am a little surprised Network Manager does not handle this. thx
EDIT: here is iwconfig output if useful in answering
wen@wen-1:~$ iwconfig lo no wireless extensions. enp2s0 no wireless extensions. wlx503eaa74d481 IEEE 802.11AC ESSID:"SINGTEL(5G)-3461" Nickname:"<WIFI@REALTEK>" Mode:Managed Frequency:5.805 GHz Access Point: E0:8E:3C:1E:34:67 Bit Rate:1.3 Gb/s Sensitivity:0/0 Retry:off RTS thr:off Fragment thr:off Power Management:off Link Quality=84/100 Signal level=100/100 Noise level=0/100 Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:0 Missed beacon:0 wlp3s0 IEEE 802.11 ESSID:"SINGTEL-3461" Mode:Managed Frequency:2.437 GHz Access Point: E0:8E:3C:1E:34:62 Bit Rate=144.4 Mb/s Tx-Power=16 dBm Retry short limit:7 RTS thr:off Fragment thr:off Power Management:off Link Quality=70/70 Signal level=-23 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:241 Missed beacon:0