I still have this problem when I use Wi-Fi to access the website or log into the app, but everything works fine with mobile data if this is not working for you, you can only wait for it to resolve itself or try complaining on every social media platform
Use mobile data
The problem is with your internet connection. It appears they either don't allow login through Wi-Fi or have restricted some IPs. I'm not entirely sure, but the issue is definitely with your internet.
I have raised my issue with both myntra and melorra, but they seem to ignore it. I don't want to cancel my order because I have been waiting for a month and melorra usually delivers in 30-40 days. So I will wait a bit more and try to escalate further.