I had this once or twice SSH to my OpenmediaVault Nas/servers. The problem is usually the Firewall on the Windows side. See here - the error being : kex_exchange_identification: read: Try disabling your Windows firewall when SSH to the device and hopefully it should connect. If you have too many SSH connections it will do the same. Windows........

@arubislander Thank you very much for the quick response! It's a shame that oem locked phones even exist. If the product is great, one should not fear competition. I'll get another phone and fingers crossed with oem unlocking possible.