VPN PPTP does not work

REPRODUCIBILITY:
OS VERSION: 5.0
HARDWARE: Jolla C2
UI LANGUAGE:
REGRESSION:

DESCRIPTION:

I noticed that native sailfish PPTP VPN is unable to connect to a VPN server. In the past with the same configuration and previous os version the connection was reached.

It seem that that depends on GRE data traffic, but that is only an hypothesis.

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ACTUAL RESULT:

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ADDITIONAL INFORMATION: