Connecting a PC to vpn via PPTP through an access point on a smartphone. What is Mikrotik missing?

Question

VPN

The Internet is distributed from an android smartphone. With windows the regular client rises the PPTP tunnel. About 30 points with different routers, 3 of them are Mikrotik. There is a connection for everything _except_mikrotik_. From the smartphone, the tunnel to Mikrotik rises normally. We conclude that the smartphone cuts something that only Mikrotik lacks. Servers on other routers without "this" raise PPTP fine. What is missing in Mikrotik for working with PPTP?
PS: I found this in the logs:
RASDiag: Mapping to new error code: 806 (ERROR_VPN_GRE_BLOCKED) instead of 721 (ERROR_PPP_NO_RESPONSE)
DwProcessProtocolFailureMessage: disconnecting VPN3-1,hEventClientDisconnect=0xffffffff
If GRE_BLOCKED is true, then why do PPTP servers work on other routers?