I have 4 USB->UART converters, on chips: FTDI232, CP2102, pl2303 and ch341.
Linux understand well all 4 converters, with out any problems.
And I have: 6 different TP-Link routers and one Netis.
All this converters works well with all routers except one: TP-Link Archer C5 HW ver 4.0
On TP-Link Archer C5 HW ver 4.0 I see normal system output, but when input see wrong chars.
For example my input: 12345
Terminal answer is: 1g233f4^Y5e
The same result in putty and screen programs.
P.S. PC system: Kubuntu 18.04 x64
User ttyUSB0 115200n8 for TP-Link
User ttyUSB0 38400n8 for Netis
The TX data on the board potentially needs a pull-up
Edit: At least I think it was the TX on the board = the RX on the adapter -- my test unit isn't immediately available. Though my last post in the preview-boxed thread suggests that I ended up pulling up the RX pin on my TP-Link