Problem with PPTP connection between 4g router and CISCO 2911?

Question

Cisco

Hello. Please help me with the following issue. In general, there is a small home subgrid of several computers 10.2.7.0/28. The main gateway is a 4G router (irz 11w on Linux) with PPTP support, through which the network goes to the Internet.
At office costs CISCO 2911 with the server lifted by PPTP. Here is the config:
version 15.0
service timestamps debug datetime msec
service timestamps log datetime msec
service password-encryption
hostname gw2911
boot-start-marker
boot-end-marker
aaa new-model
aaa authentication login default local
aaa authentication login L2TPauthenList local
aaa authentication login userauthen local
aaa authentication login users local
aaa authentication ppp default local
aaa authorization network default local
aaa authorization network L2TPauthorList local
/* assign subnets to a specific ip */
aaa attribute list client1_ip
attribute type addr 172.22.16.2 service ppp protocol ip
aaa session-id common
no ipv6 cef
ip source-route
ip cef
ip domain name info.ru
multilink bundle-name authenticated
vpdn enable
vpdn-group 1
! Default PPTP VPDN group
accept-dialin
protocol pptp
virtual-template 2
l2tp tunnel timeout no-session 15
license udi pid CISCO2911/K9 sn FCZ142971PT
username admin privilege 15 password 7 ****************
username client1 privilege 15 password 7 ****************
username client1 aaa attribute list client1_ip
redundancy
ip ssh version 2
interface Loopback10
ip address 172.22.16.1 255.255.255.255
interface GigabitEthernet0/0
ip address 92.50.151.139 255.255.255.248 (internet on cisco)
duplex auto
speed auto
!
interface GigabitEthernet0/1
ip address 192.168.202.3 255.255.255.248 ( main office LAN gateway )
duplex auto
speed auto
no cdp enable
interface Virtual-Template2
ip unnumbered Loopback10
ip virtual-reassembly
peer default ip address pool pptp_pool
no keepalive
ppp encrypt mppe auto
ppp authentication chap
ip local pool pptp_pool 172.22.16.2 172.22.16.5
ip forward-protocol nd
no ip http server
no ip http secure-server
ip route 0.0.0.0 0.0.0.0 92.50. 151.137 (main internet gateway)
ip route 10.2.2.0 255.255.255.0 192.168.202.2 (local office)
ip route 10.2.7.0 255.255.255.240 172.22.16.2
control-plane!
line con 0
line aux 0
line vty 0 4
transport input ssh
scheduler allocate 20000 1000
PPTP client is enabled on the 4G router and the home subnet is connected to the main office. The home subnet sees the office, pings, etc.
But the OFFICE sees nothing but a 4G router 10.2.7.1 (gw home).
Ping writes: "The specified port is not available", and tracert from the main office to computers from the home subnet reaches 172.22.16.1 and writes that "the specified protocol is not available"
Please also explain the meaning of the line "ip route 10.2.7.0 255.255.255.240 172.22.16.2" . If we assigned an ip to the client, why write this, but it doesn’t work without it.
Why is the main office and cisco also seeing a 4g router, but not seeing anything behind it. I beg you to help, I've been fighting for a week now. Thanks in advance.

Answer 1

ip route 10.2.7.0 255.255.255.240 172.22.16.2

this is the route to the home network, 172.22.16.2 is the IP received by the PPTP client on the 4G router.
The focus needs to be transferred from Cisco to the 4G router, since the home network sees the office, but the home office does not, it looks like the 4G modem has NAT configured over the ppp interface, which needs to be disabled. You can verify this by running a sniffer on some computer in the office and pinging it from the home network, the srcip will probably be 172.22.16.2, not the IP of the machine.

Answer 2

Here is a report from a sniffer when I ping a computer in the office from my home network.