Combine 2 mikrotiks on the main static on a remote modem E3372h HiLink with a Tele2 SIM card?

Question

linux

People need help!
There is a MikroTik RB951Ui-2HnD connected to it by Rostelecom PPPoE with static.
Internal network 192.168.10.0/24
Elsewhere is MikroTik hEX PoE lite, the E3372h modem is connected to it, it is stitched into HiLink with a SIM card from tele2.
Internal network 192.168.5.0/24
The task is to combine the Main Router RB951 with the office hEX for its remote management.
Initially, instead of the E3372h modem, there was a cable and there was a PPPtP tunnel between the Mikrotiks and everything was great.
When the modem was installed, it was impossible to combine Mikrotiki, all attempts were exhausted.
I understand the problem is in the modem.
Describe who knows what needs to be done and if possible in more detail for dummies)) :)

Answer 1

deploy a VPN server on a tick with statics, on a tick with a modem - a VPN client,
any manual will do just fine