I've just tested 4.2.1 and it also has the DHCP bug. I really believe every version ever of the ObserverIP has had this issue since day one.
There are several possible reasons you may not feel it is a problem. It could be because your DHCP lease may be long (days or weeks). Then when it expires it reboots and you just don't notice it as it may be infrequent. Depends on what your DHCP lease time is set to on your router. But even still it actually keeps running with the existing IP after it expires for some time. It depends on the router if and when it wants to kick the device off the network because it doesn't have a valid lease. The fact is that the ObserverIP is not handling DHCP via industry standards. The ObserverIP it is doing its own thing and different networks may react differently to its non-standard way of running. Eventually when the ObserverIP gets kicked off the network then 20 minutes later it has a check loop to detect that it has fallen off the network and it reboots and then it grabs a new DHCP lease. This is just not the right way at all for any network device to be acting. A DHCP lease is actually supposed to be renewed at the half life of the lease. You can check with the DHCP server the status of leases and you can see when they renew. With the ObserverIP you can watch the lease half life come to be and it keeps running without renewal. Then at expiration time it also doesn't renew then. A proper DHCP server is supposed to drop that client address that choose not to renew (normally because it isn't on the network).
There are several possible reasons you may not feel it is a problem. It could be because your DHCP lease may be long (days or weeks). Then when it expires it reboots and you just don't notice it as it may be infrequent. Depends on what your DHCP lease time is set to on your router. But even still it actually keeps running with the existing IP after it expires for some time. It depends on the router if and when it wants to kick the device off the network because it doesn't have a valid lease. The fact is that the ObserverIP is not handling DHCP via industry standards. The ObserverIP it is doing its own thing and different networks may react differently to its non-standard way of running. Eventually when the ObserverIP gets kicked off the network then 20 minutes later it has a check loop to detect that it has fallen off the network and it reboots and then it grabs a new DHCP lease. This is just not the right way at all for any network device to be acting. A DHCP lease is actually supposed to be renewed at the half life of the lease. You can check with the DHCP server the status of leases and you can see when they renew. With the ObserverIP you can watch the lease half life come to be and it keeps running without renewal. Then at expiration time it also doesn't renew then. A proper DHCP server is supposed to drop that client address that choose not to renew (normally because it isn't on the network).