I've installed pptpd and trying to connect my devices to internet through VPN on Linode VPS.

I've used several guides and forum threads:
viewtopic.php?t=4474&highlight=pptpd
viewtopic.php?t=3096&highlight=pptpd

# apt-get install pptpd
# vi /etc/pptpd.conf
localip 10.60.60.1 
remoteip 10.60.60.50-150
# vi /etc/ppp/pptpd-options
ms-dns [DNS1 IP]
ms-dns [DNS2 IP]
# vi /etc/ppp/chap-secrets
myusername pptpd mypasswd *
# mknod /dev/ppp c 108 0
# /etc/init.d/pptpd restart
# vi /etc/sysctl.conf
net.ipv4.ip_forward=1
# sysctl net.ipv4.ip_forward=1
# iptables -t nat -A POSTROUTING -s 10.60.60.0/24 -o eth0 -j MASQUERADE

Windows XP connection - ok.
Android (HTC Desire) - connects, works for a few minutes and then floods /var/log/messages on the VPN server with "Protocol-Reject for unsupported protocol ..." errors. No disconnect, but no internet.
iPAD - connects, successfully pings sites with zTools, but Safari does not opens sites.

Could you please help me if you have any ideas on how to troubleshooting the connectivity issues on Android and iPAD.

Thanks,
Alex

Updated original post with new question.

Put this line in your options.pptpd file :

mtu 1400

and also check out for gre protocol and 1723 port are open.