Trying to connect a USB Dewpoint controller to my Linux Mint INDI server. Unfortunately I cannot get the connection to work and get a Handshake and timeout error:
2018-11-14T22:04:25: [ERROR] HandShake error: Timeout error.
2018-11-14T22:04:22: [INFO] USB_Dewpoint is online. Getting device parameters...

Other devices using USB-serial converters working well (using ttyUSBn though). On the Mac, connection works perfectly.

Anyone who may have an idea what this is and how this can be solved?

This is usually caused by ModemManager writing AT-command to the device as it for some reason advertises itself as communication class USB device and there is no direct way to synchronize commands and responses with the device due to its protocol. Are you using version 1.0 or 1.1 of the driver? 1.1 tries to resync the communication, which might help, but otherwise either removing or disabling ModemManager is also worth a try.

Thank you jpaana, that was the issue.
First upgraded from version 1.0 to 1.1. This enabled the communication, but gave some kind of sync error. After 6 or so tries it stopped.
Then I removed the modemmanager and that seemed to be the culprit, as it worked flawlessly afterwards!

Good, yes the resync feature tries get an error out of the device, which would indicate a sync point in the protocol and sometimes it works, sometimes not, but it's obviously better to avoid it in the first place