Can't setup svn server?

Question

linux

Good day.
For the 2nd day I can not set up the svn server. Or rather, I can not make it so that it is not available from the local network.
More: there is an old system unit. It has debian lxde on it. Router - dlink dir 300.
You need to make sure that you can connect to the svn server from the global network.
In the router settings, I added a virtual server, allowed all connections to port 3690.
In linux, I'm stupid with iptables. I'm trying to allow all connections, but the following problem occurs: input permissions are added, but for some reason forward is not saved.
As a result: on public ip everything responds. On the local network, the connection to svn is successful. If I try to connect to svn using a public ip with the wrong port, I immediately get an error: connection refused. If you try to connect with the right port, the svn client hangs for a minute, and then issues: "Can't connect to host 'host': Operation timed out".
Help me to understand

Answer 1

You should buy a VDS with an external IP and move the SVN server to it. At least it will cost less than electricity to your server.

Answer 2

Help: Apache as VisualSVN server

Answer 3

Dig in SVN already, switch to git or mercurial. And it's easier to develop and commit and deploy.

Answer 4

Why do you need forward in iptables?
What do you dislike about Input accept?
How can port availability be checked by ICMP requests?
I give you curl and telnet