Cant reset wifi connection after change of router

Changed our internet service provider so have tried to update the wifi settings for the inverter but it seems to be stuck - I reset the dongle but its dropped into broadcasting its core network HF-A21x_AP not the wifi network shown on the label on the inverter.
Not a problem in its self because I have accessed the dongles configuration page and input my Router details but once i have done that and asked it to reboot it just gets stuck in rebooting
I have tried turning off the 5Ghz broadcast on the router, and double checked i have input the details correctly and repeated the process multiple times, Ive even tried rebooting using a mobile hotspot from my phone - nothing seems to work so i cant get the inverter to join our home network…

any suggestions welcomed