[Bug] After some time since homebridge start, CoAP Messages are no longer received
**Describe the bug**
I use homebridge-shelly and after the service starts the devices are online and frequently after 15 seconds updated. After 3 minutes the device page gets no longer updated and the device can only get controlled. After checking the wiki page about the issues with multicast traffic I checked the interface with tcpdump. All updates are coming in but homebridge-shelly and neither the node-shellies application are receiving or using these messages. The service stays online with the listening address 0.0.0.0:5683 but the application does not use the incoming packages anymore.
After I restart homebridge or "shellies listen" the device Updates are shown but only for about 3 minutes...

I have 2 interfaces on my homebridge server. One for management and WAN and a separate VLAN for the IoT devices where the shelly devices are in. Multicast messages are successfully reaching the server while homebridge-shelly is running.

**Log output**
Nothing shown in the log about this...

**Environment:**
 - Shelly device(s): Shelly Dimmer, Shelly 2.5
 - Plugin version: 0.15.4
 - Device running homebridge: Fedora 32 virtual machine
