apache - Magento frontend redirect error while using reverse proxy -

we've been struggling problem involving magento website , reverse proxy.

server used reverse proxy (apache) , redirects incoming subdomain.domain.com/appname local-ip/appname hosted on server b (apache well).

what weird works fine on backend. can login, modify stuff, normal there.

but on frontend nothing works , there infinite redirection.

however setting magento local-ip/appname base url, , accessing through subdomain.domain.com/appname (not local-ip/appname) works fine if accessed local network.

as magento uses adress subdomain.domain.com/appname base url, frontend gives infinite redirection error.

if has input on appreciate.

thanks!

for record, reverse proxy needed directive

proxypreservehost on 

as set off default there infinite redirection magento trying access external address transformed local ip reverse proxy ans on. proxypreservehost on reverse proxy transmits original url website behind him. consequence magento can set external address base url.