VPN suddenly stopped working, now giving Error code 1.

[micromac]

Hello,
I recently configured a corporate VPN using SoftEther, hosted on a local server in order to give LAN access to 2 remote clients.
It was all working fine (tested for various days with different workloads and so on) when, after almost a month, it suddently stopped working, giving back Error code 1 when trying to connect to it.
I looked up the SoftEther log file but it simply says that the (at the time) active connection was terminated, without any additional information.

Has this ever happened to anyone else? Has this a known solution that I'm not able to find?

Thank you all.

[shakibamoshiri]

if no one touched anything it could network issues (ISP) or firewalls (ISP).
More info is needed to narrow down the issue
- which version of SE
- which OS was installed on
- which protocol(s) clients use
- etc