Good broadband but no wifi

Hi, I renewed my broadband and phone contract last Tuesday. On Wednesday after work, I realised that most of my devices had disconnected from the WiFi. I tried to reconnect repeatedly over the next few days, after work, assuming it was my bad tech knowledge that was failing especially as my broadband was working. All devices connected by lan cable worked properly.  Rang virgin on Sun. Adviser confirmed that there was no issue with my broadband. We tried various things,resetting the router, router on and off, forgetting network and trying to reconnect. No joy. He ordered a new router. That came today. Set that up successfully. Again good broadband and working beautifully via lan cable but no wifi. Except bizarrely, connected to my printer wirelessly. Rang virgin again. The adviser couldn't explain what the problem might be. Is arranging and engineer for tomorrow. I feel like this is a problem which happened when I renewed and if that's the case, should be fixable remotely. Has anyone else experienced this and how was it fixed please?