GOING-LOCO

Hi I wondered if you could help me I have the z21 which for 2 years has run on my home network. I recently decided to run my Virgin router as a modem and use my own router which is the ASUS gaming router and has the new faster wifi protocol. Anyway my z21 stopped working. I decided to reset it back to factory settings and for now use it with the originally supplied router. I can connect to the tp link no issue but I cannot conect to the z21 I have tried everything pc directly conected, I-pad, Samsung s20 with android but nothing will work. I decided to set up the system as it was when working with the virgin router as a router again and everything worked perfectly again. I am at a loss as the z21 settings are as factory set. To connect to my new router which setting do I need to change I do understand networking but am not an expert but cannot remember which setting I need to change for it to work through my new router. I used the virgin router originally without having to change any settings and because I could never get the TP-LINK to work I would greatfully appreciate any help.