When I open a website in Chrome or in Edge I receive a 403 Forbidden error when on the server. Off the server it works fine. Can you help?

Exact same issue in Firefox as chrome and edge for

It is probably caused by how Amazon hosts your web site. An nslookup shows that there are 3 IP addresses assigned.

C:\>nslookup www2.lawngateway.com

Non-authoritative answer:
Name:    realgr-publi-tog640z9uz0w-1859478684.us-east-1.elb.amazonaws.com
Addresses:  54.84.7.129
          54.225.70.40
          3.210.233.185
Aliases:  www2.lawngateway.com
C:\>

If your server is sitting behind a firewall or a content switch, then the HTTP request may not be able to be routed/forwarded "back" to the server that is making the request. Amazon may also be doing something with HTTP header values when the request come in from the internet.

I would suggest that you start by ensuring that every web site on your server has a default page that provides enough information that you can use to determine which site it went to.

I tried browsing your site and there is no default page, just a 403 error.

Also check your IIS logs to see where the request is going. For testing I sometimes put something unique in the request and then search the logs for that string. "PleaseFindMe" for example.

https://www2.lawngateway.com/lawnsquad/Login/PleaseFindMe

Depending on your IIS bindings you may also be able to override DNS with host file entries that eliminate any outbound network traffic. Use notepad and add and entry for "127.0.0.1 www2.lawngateway.com" to your hosts file.

Exact same issue in Firefox as chrome and edge for https://www2.lawngateway.com/lawnsquad/Login/OfferCode/?code=1A4T211IGZ and all users have issue.