Hi Dolomats0,
Hope you are well today!
There is no need to use both Varnish and Nginx as you can configure Nginx to be configured as proxy cacher too.
If I am going to use Varnish it will be with Apache2 rather than Nginx.
My personal reason behind this is because I find Apache2 far more easy for administration, and needs less attention. Nginx is very versatile, but it squeeze more of my time.
Or maybe I am just old-minded and believe that a piece of software should just do one thing, and do it good.
There is opninions from both sides – one saying Varnish is better for caching and the other that Nginx is the only thing you need.
Anyway – in short you shouldn’t have any problems using both, as long as they are configured properly. But I will personally go with either: Apache+Varnish or just Nginx
You should be careful not to drop the cookies in your configuration in Varnish and Nginx.
You can also might these links interesting:
https://www.uptimemadeeasy.com/cloud/nginx-or-varnish-which-is-faster/
https://www.narga.net/varnish-nginx-comparison-nginx-alone-better/
Thanks,
Ivan