Latitude E7270 and Pro3x dock issues

We have recently set up about 700 Latitude E7270 with docking stations and are experiencing several issues with, so far, 10%. Issues are mainly repeating letters, mouse hangs, screen flashes (connected to Dell U2715H thorugh the docking station) and the wifi is quite erratic.

We have tried every combination of usb connection, mouse/keyboard to dock usb3, usb 2, mouse keyboard to USB hub in monitor, and the issues persist. We have tried connecting to network through ethernet to no avail, updated bios/firmware, updated drivers, changing screen refresh rate from 59 to 60hz, and still issues persist.

The only surefire workaround has been to disconnect the dock and connect mouse, keyboard and monitor directly to the laptops.