git error: fatal: The remote end hung up unexpectedly. Why?

Question

git

Hello!
I had to set up a git server on a Windows machine.
Server in the corporate network, access to it from the outside via OpenVPN, because access is needed not only for git, but also for example for RDP, etc.
I lifted everything according to the instructions .
As a result, any operation with the repository on the server ends with an error:
fatal: The remote end hung up unexpectedly
At the same time, the ssh console opens normally and everything works.
On the internet, this error mostly occurs when git operations go over http, but mine is ssh.
Afternoon fiddling with rechecking settings and googling, replaced Win32_OpenSSH with Bitvise SSH Server.
At first, the error disappeared and I was able to push and clone the repository from the server via ssh. But the next day everything started again - the same error on any operation with a remote repository.
Standard manipulations - reboot and update did not give anything.
Turned on git tracing on both sides, SSH server logging - no suggestive errors or anything that could help solve the problem. I replaced the standard ssh client on the client side with plink from putty - to no avail.
If who faced such error, prompt where to dig further.
Additional information:
Clients are still the same on Windows, but Linux is also planned.
The VPN exchange rate between the client and the server is not large, the ping delay is 160 ml.sec.
PS: at the moment I have raised git daemon - everything works fine with it, I also shared the directory with repositories - the same works through files.
But I would like to deal with the work on ssh.