We are testing several Lenovo Tab 4 Android (7.1.1) tablets as telnet clients over wireless LAN for part tracking (barcoding reading) in our manufacturing plant. Hopefully, these will soon replace very expensive Honeywell handheld computer/scanners that ride on every forklift. These handhelds have hardware keyboards, and the software they communicate with through telnet have no problems reading function key codes sent.
On the tablets we are using the Termius ssh/telnet client with the Hacker's Keyboard app, and it worked perfectly until last week. Suddenly the effect of tapping on a function key equaled the effect of tapping the ESC key, which basically causes the program to exit whatever form is active and return to the parent menu.
According to the settings for all related apps, the versions have not changed since everything was working, and there is no sign that any of the settings for the apps have been changed. We get the identical behavior on all tablets.
On one of the tablets, I have installed and tested several other (the most popular) ssh/telnet clients and do not have any problems with function keys. However, none of these alternatives provides a setting that allows "keep alives", or connection persistence, etc. that can keep the connection from timing out after 60s of inactivity. So that presents a completely new problem. Termius will stay connected all day if you like. We only need 5 min, and that's how it's configured. BUT, function keys don't work any more. So it comes down to "live with 60s timeouts" or "live with no function keys". Neither is acceptable.
PS: There were no changes to our barcode system server, or to LAN configuration, from the time the function keys worked until they didn't.
I'd appreciate any help or suggestions for next steps.
