Cache Proxy have following limitation:
1. Edge Cache proxy did not cache the pages on which Tab Menu – Page Builder theme is applied. If you will change the theme to Portal, PortalWeb2 or any of your customized theme it will start caching the portal theme contents. There might be other reason that Tab Menu theme is deployed as web module.
2. In order to cache the portal pages please make sure you have assigned anonymous access to pages and portelts. Because as per my knowledge CP only cache public contents. Also verify that Cache-Control: public header by collecting cache proxy traces. Follow the link under references labeled MustGather.
3. In order cache wcm contents please make sure that wcm site can be access by public users. In order to assign public access to a wcm site please follow the link under reference labeled Anonymous Access WCM items:
4. After assigning the public access please verify on Proxy Access Statistics page that wcm contents have context /wps/wcm/connect NOT /wps/wcm/mycnnect.
5. Even after assigning the public access we noticed that cp was not caching the wcm contents. After following up for few weeks with IBM support the issue remained same. Thanks to my colleague and friend Kashif Memon who discovered the following directives and resolved the issue:
CacheQueries ALWAYS http://mysite.com/*
CacheMinHold http://mysite.com/* 1 hour
MustGather CP: http://www-01.ibm.com/support/docview.wss?uid=swg21141054