W3 in Root site cache Blocking valid URLs in subfolder site

Puzzling…

I moved my membership site to a subfolder installation of WP for several reasons. the root site is mostly sales pages and blog and I’d like to cache and run a lot of plugins that are unnecessary on the membership area and I’d like to run different themes – a faster leaner them for the member site…

So I changed the structure to 2 WP sites
singing.com – now sales and blog only, removed membership
singing.com/members – the new WLM site

This has worked great for about 3 months with no problems in the structure. I even made the menus and looks/feel so much alike that it’s hard to tell when you move between the different sites – great!

SUDDENLY CUSTOMERS CAN NOT ACCESS PRODUCTS – PAGE NOT FOUND

Here’s a URL for downloading one of my products (should be nicely protected)

https://singing.com/memb…..taller.exe

To increase load speed on the root sales pages site (no membership there) I added W3 Total Cache specifically. It worked great for a few days..

…Until today… PAGE NOT FOUND

The problem appears to be the caching in the Root site… A plugin needed an update, an another plugin may have auto updated putting W3 in a state of recommending to manually flush the cache. When I manually cleared the cache the PAGE NOT FOUND problem went away.

The disturbing part is that the Cache in Site1 was blocking access to Site2.

when searching for singing.com/member/…download link… the system went to the cache manager of the root singing.com – and the cache manager decided to handle it rather than pass it on to the other site.

It’s clear this was happening because the page not found error was clearly from the Site1 root site and not the same page not found on the other site 2.

Some questions:
1) How does the hand-off normally work? It seems clear the root site is catching the look up because the page not found comes from the root wordpress, not from the membership wordpress install.

2) Is there some way to specify for W3 to ignore certain prefixes of URL? eg, site1/membership/

3) Is there a way to have the membership installation handle the look up when you’re in the membership area?

4) Maybe a better written rules in .htaccess?

Thanks for any guidance on this.

Peace

https://www.ads-software.com/plugins/w3-total-cache/