F-Secure SENSE Router port forwarding issue in firmware version 1.7.104.20

Symptoms

After the firmware update in version 1.7.104.20, port forwarding rules are not working.

Diagnosis

This issue is due to the recent enablement of the multicasting functionality in firmware version 1.7.104.20, which causes user-defined port forwarding rules to be overwritten by a new IP table rule.

Solution

Set up port forwarding rules again.
Please refer to this How to set port forwarding on F-Secure SENSE Router on how to set port forwarding.