F5 load balancer with 2 IIS server - First login always Invalid post request

PHPMaker v2024.4I setup 2 IIS servers running my PHPMaker project and have F5 load balancer to route to either of the servers.I set my project login page on my Microsoft Edge startup page. Every time I launch Edge, it will go to my login page but it will always show the below error when I login. I need to resubmit the URL again from the address bar so the page will refresh before I can login without error. I can consistently simulate this error.

400 
Bad Request
Invalid post request

Any idea why this happen? I don’t want to disable “check token for form post”.

You may enable Debug and also check HTTP response to see the error in more details.