User Agent issue

We use the following method to serve different content to various devices:

<?php if ($os_platform == "ios iphone" || $os_platform == "android" || $os_platform == "blackberry" || $os_platform == "ios ipod") {  ?>
<em>/* The content for those devices */
</em>
<?php } else { } ?>

…

The issue is that content meant for these specific mobile devices is also being served to users on devices like iPads.

For example, it appears that if the visit that triggers the cached page is from an iPhone, all iPad users will receive that content. If an iPad visit triggers the cached page, iPhone users will see the content meant for the iPad.

Separate content is served to these devices – as intended – when W3 Total Cache is deactivated.

I’ve enabled User Agent Groups and added user agents to both high and low fields (list below).

It seems that the cached content is not distinguishing between some different “mobile” devices – in this case iPhone and iPad.

Any help to resolve would be much appreciated. Thanks.

USER AGENT
HIGH
acer\ s100
android
archos5
bada
bb10
blackberry9500
blackberry9530
blackberry9550
blackberry\ 9800
cupcake
docomo\ ht\-03a
dream
froyo
googlebot-mobile
htc\ hero
htc\ magic
htc_dream
htc_magic
iemobile/7.0
incognito
ipad
iphone
ipod
kindle
lg\-gw620
liquid\ build
maemo
mot\-mb200
mot\-mb300
nexus\ 7
nexus\ one
opera\ mini
s8000
samsung\-s8000
series60.*webkit
series60/5\.0
sonyericssone10
sonyericssonu20
sonyericssonx10
t\-mobile\ mytouch\ 3g
t\-mobile\ opal
tattoo
touch
webmate
webos

LOW
240×320
2\.0\ mmp
\bppc\b
alcatel
amoi
asus
au\-mic
audiovox
avantgo
benq
bird
blackberry
blazer
cdm
cellphone
danger
ddipocket
docomo
dopod
elaine/3\.0
ericsson
eudoraweb
fly
haier
hiptop
hp\.ipaq
htc
huawei
i\-mobile
iemobile
iemobile/7
iemobile/9
j\-phone
kddi
konka
kwc
kyocera/wx310k
lenovo
lg
lg/u990
lge\ vx
midp
midp\-2\.0
mmef20
mmp
mobilephone
mot\-v
motorola
msie\ 10\.0
netfront
newgen
newt
nintendo\ ds
nintendo\ wii
nitro
nokia
novarra
o2
openweb
opera\ mobi
opera\.mobi
p160u
palm
panasonic
pantech
pdxgw
pg
philips
phone
playbook
playstation\ portable
portalmmm
proxinet
psp
qtek
sagem
samsung
sanyo
sch
sch\-i800
sec
sendo
sgh
sharp
sharp\-tq\-gx10
small
smartphone
softbank
sonyericsson
sph
symbian
symbian\ os
symbianos
toshiba
treo
ts21i\-10
up\.browser
up\.link
uts
vertu
vodafone
wap
willcome
windows\ ce
windows\.ce
winwap
xda
xoom
zte

https://ww.wp.xz.cn/plugins/w3-total-cache/