Home Assistant suddenly no longer accessible. err_connection_refused (VPN - vacation)

Hello everyone,

I hope I’m in the right subforum with my question. If not, sorry! And of course, feel free to move it.

I’m having a problem accessing my Home Assistant. We’re currently on vacation in the Netherlands, and I’m using a VPN connection via my FritzBox to control basic building functions (shutters, lights, etc.) while on the go. For this, I’m using the VPN function integrated into the MyFritz! app. Since this morning, I’ve suddenly been getting the error “err_connection_refused” in Chrome. The strange thing is that I was still using Home Assistant a few minutes earlier and didn’t change anything in the configuration or anything else.

Suddenly, it just doesn’t work anymore for no apparent reason. I run Home Assistant in a VM on a QNAP NAS. I can access everything else in my network and can see that the VM is running. The FritzBox also shows the VM under the known IP address, so everything is as usual, except that I can no longer access Home Assistant. Unfortunately, access to the FritzBox is somewhat limited when I’m on the go, as I have to make entries on the DECT phones to change basic settings.

However, I haven’t made any changes to the FritzBox or the home network before.

I am at a loss as to what the problem is.
I am grateful for any advice and hope that I can somehow solve this problem from here.

Thank you in advance for any advice.

Best regards,
Daniel