I was able to fix the issue. I added SITEURL and HOME with the Nginx IP address in wp-config.ph file from both hosts and it fixed the issue. Just wanted to post the answer just incase someone is new like me and have similar issue.
define('WP_SITEURL','http://192.168.1.226');
define( 'WP_HOME', 'http://192.168.1.226' );
I have another question: Can someone help? I tried to search for it in the documentation, but I couldn't find it. I might not have used the right keyword. How can I use Nginx as a proper load balancer for all websites? I mean, how can I add other websites? For example, I have already added two WordPress websites, and the load balancing is fine. If I added two Nextcloud websites and Confluence websites, Do I need to use different ports for each web service? I mean, how can I have multiple entries in the same nginx config file?
Appreciate your help!