Outlook Mobile App and Web Access

[nwfortinet]

Hi, i need some help on this matter. After changing Fortigate 50E config to PPPoE (before the change it's working) some of the users cannot configure Outlook mobile app for new setup and if configured already seems cannot send and receive mail. Cannot even access our web mail. But for some of our co-worker they can access this with no issue. Troubleshooting done tried to connect from SIP router to a WIFI router through PPPoE working if Fortigate not connected. extended ping 10K no packet loss. Packet snipper traffic can pass but seems no reply to the destination but by tracert i can reach the destination i can ping. Tried allow microsoft app o365 in app control same issue. tried to create policy all microsoft in addess object an internet service same issue. no deep inspection. even no inspection or with ssl inspection same issue. Seems mobile is not the isse because i tried by mobile data it's ok even with VPN it's ok.

Like this forum.fortinet.com if I'm not connected in VPN (ultrasurf) it will not open.