My ac1200 6120 won’t even even connect to my wifi router anymore

I doubt if anyone can help on the basis of that information.

 

Don't cram everything into the subject. Write something that explains what equipment you are using – what is this ac1200? – and what happens.

 

You can help people to help you by providing the information suggested in this forum's header:

 

Subject (Include model number and brief summary)
Model (Recommended - Helps the community give the best answers)
Body (Include additional detail including model version, firmware, OS and environment where relevant.)

They are there for a good reason.