How to recover from DHCP Renewal and Rebind failures?
Possible causes:


The DHCP server might be down.
Or it might have lost its state (but I think they try really hard to preserve the list of leases).
Or some other cause which makes the server unavailable/unwilling to renew the lease.


Solutions:


If you can wait, you can retry, but otherwise I'd just say try to obtain a new lease, unless for some reason you really want to stick to the IP from the previous lease.
If you control the server and your network is kinda stable, you could assign a fixed IP to your device configure the server to associate it with the MAC address you gave to your device. In general, when the network setup is really stable, this might be preferable, since other entities on the network will probably cache the IP of your device and use it, should the DNS fail as well (ex: dnsmasquerade works both as dhcp server and dns). Similarly, your device doesn't have to worry anymore of the DHCP lease, because it's permanent.