Edge Client (Win) Caches Initial Server URL

This is the normal behaviour.

AFIK,the solution for this is a 'Redirect 302' as explained:

1) Need 4 public IP address, and 3 domain names

   f5.mydomain.com   - IP1 (apm1 VS with redirect iRule)
   apm1.mydomain.com - IP1a(apm1 SSL VPN VS)

   f5.mydomain.com   - IP2 (apm2 VS with with redirect iRule)
   apm2.mydomain.com - IP2a(apm2 SSL VPN VS)

2) EdgeClient f5.mydomain.com resolves to IP1 or IP2 as per GTM

3) When EdgeClient hit IP1(on apm1), do redirect to apm1.mydomain.com

    when HTTP_REQUEST {
       HTTP::respond 302 Location "https://apm1.mydomain.com[HTTP::uri]"
    }

4) When EdgeClient hit IP2(on apm2), do redirect to apm2.mydomain.com

    when HTTP_REQUEST {
       HTTP::respond 302 Location "https://apm2.mydomain.com[HTTP::uri]"
    }

 Hope it works for you.