Hello,

Yes, this would not be a problem. What you would need keep in mind is:

• Make sure that the Strapi and the Node.js applications are running on different ports, for example, start Strapi on port 1337 as suggested in the documentation.

• You can take a look at the steps on how to install Strapi on a DigitalOcean Droplet here:

https://strapi.io/documentation/3.0.0-alpha.x/guides/deployment.html#digital-ocean

• Then you can start Node.js on port 8080 for example.

• Finally install Nginx and set it up as a reverse proxy for your Node.js application:

https://www.digitalocean.com/community/tutorials/how-to-set-up-a-node-js-application-for-production-on-ubuntu-16-04

• Also if needed you can create a second Nginx server block for your Strapi app and set the server_name to your admin.domain.com subdomain name as you mentioned. The Nginx proxy rules that you would need to add for the Strapi application would be a bit different to the Node.js ones, you can use the following:

proxy_pass http://localhost:1337;  
proxy_http_version 1.1;  
proxy_set_header Upgrade $http_upgrade;  
proxy_set_header Connection 'upgrade';  
proxy_set_header Host $host;  
proxy_cache_bypass $http_upgrade; 

Hope that this helps!
Let me know if you have any questions.
Regards,
Bobby