Did you put this part in the right place? Because surfing to http://zepling.com.np/.well-known/acme-challenge/ also gives a 404 file not found. I assume it would give me a 403 Forbidden-error if the location/root part to /etc/letsencrypt (which by the way isn't a very good path I'd recon, now people could download content of that directory if they'd like) is working.
Hmm, this is also a very curious reply from your webserver:
```
osiris@erazer ~ $ curl -v http://zepling.com.np/.well-known/
* Trying 18.188.214.171:80...
* TCP_NODELAY set
* Connected to zepling.com.np (18.188.214.171) port 80 (#0)
> GET /.well-known/ HTTP/1.1
> Host: zepling.com.np
> User-Agent: curl/7.66.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 401
< Server: nginx/1.17.8
< Date: Sun, 02 Feb 2020 15:39:58 GMT
< Content-Type: application/json
< Content-Length: 81
< Connection: keep-alive
< X-Content-Type-Options: nosniff
< X-XSS-Protection: 1; mode=block
< Cache-Control: no-cache, no-store, max-age=0, must-revalidate
< Pragma: no-cache
< Expires: 0
< X-Frame-Options: DENY
<
* Connection #0 to host zepling.com.np left intact
{"error":"Authentication Error.","message":"Username or Password doesn't match."}osiris@erazer ~ $
```
It outputs a JSON file? Why? I'd say we'd need your entire relevant nginx configuration, because there's a lot more going on than just that location directive.