I did at!selrat=20 for 5G only but now only issue is it seems by EM9191 has trouble holding a connection. It works well but when I walk away and come back it loses connection until I reissue DHCP, any idea why?
do you mean 5G n71 SA still have problem in both linux and windows that it will lose connection sometimes?
How do you set for AT!BAND command for 5G SA n71 band?
Do you see such problem in 5G NSA (ENDC) mode?
FOR ANYONE LOOKING FOR ANSWER TO ORGINAL QUESTION IN SUMMERY:
My modem was in MBIM mode meaning that to get it started in Linux once drivers installed you must you command “sudo mbim-network /dev/cdc-wdm0 start” your wdmX may be different based on number. After you get a message stating that it is started correctly you can issue “sudo dhclient wwan0” onto the interface. I had a DNS issue that was then causing disconnects which I resolved via “sudo apt-get install resolvconf” and populating the /etc/resolvconf/resolv.conf.d/head file with:
nameserver 1.1.1.1
nameserver 1.0.0.1
Which made everything work the way I needed it to. Further I used 5G only by using AT!SELRAT=20 but you could set to any by using AT!SELRAT=? and choosing from the list. Using AT!BAND=X did not work for me and would cause me to lose registration. After issuing my AT!SELRAT=X command I also issued AT!RESET to save and restart modem.