Can't connect to router after installing SSL certificates

I accessed my GL-AXT1300 router via WinSCP, and went over to /etc/nginx.

I renamed the nginx.cer to nginx.cer_old and nginx.key to nginx.key_old.

I then uploaded by own SSL certificate and key and renamed them to nginx.cer and nginx.key

Now my router refuses to load up the interface and I can no longer access it via WinSCP.

Somehow I am able to connect to the WiFi network and have internet.

Can someone kindly help me resolve this?

It should be not the case. Nginx and SSH are entirely different.
Can you still SSH into the router?

A reset might be the fastest way to get the device running again. Changing the cert does not make much sense anyway - what did you expect?

This router has a self-signed SSL certificate, making browsers report invalid certificate status and preventing access to WebDAV sync utilities, for example EasySync on android.

Update: reset the router and repeated the process. Now it’s operational, but I’m still getting invalid certificate errors even though I uploaded an SSL cert I purchased recently. Anyone know why that is?

Which is totally fine for some device at home. You can always skip these warnings or import the cert to the trust store of your device. If EasySync does not support self-signed SSL you have to use a trustworthy one, indeed.

How do you access the router? You have to use the FQDN then.
And you need to restart nginx after you changed the files.