When I rebooted the router he didn`t find my NAS.
The router is not supposed to do so. It's the nas who has to find the router. When the network goes 'up', due to boot, or due to an inserted cable, the box broadcasts a DHCP request. The router receives that, and assigns an IP address. (And in the same package, it also bundles information about gateway, dns, ...) From that moment on, the router 'knows' the NAS.
When the NAS didn't show up in the clients list, that means that either the router is broken (I guess you wrote your question using that router, so that is unlikely) or the nas didn't request an address.
The nas can have a fixed IP assigned, or the nas didn't detect the router reboot (which can be the case when there is a switch between the router and the nas, the nas is broken, or the update caused a network incompatibility.
In the Iomega subforum there are several reports of an HMNHD-CE (almost the same hardware) which cannot connect to certain Gige-switches.
Does the network led light on the nas (does it have
a network light?) and on the switch/router port?