The problem with mod_remoteip is that it is currently (first reported in 2013 [1]) broken in a setup where apache 2.4 is used behind a reverse proxy. remoteip module changes the client IP address (%a) but does not change the host name (%h or REMOTE_HOST passed to other modules, resolved via HostNameLookups On/Double).
apache2 2.4.10-10+deb8u4 and libapache2-mod-rpaf=0.6-13 do not suffer from that problem. [1] https://bz.apache.org/bugzilla/show_bug.cgi?id=55348 -- Konstantin Pavlov
