@Harpo 

When this happens we will typically recommend to default your router and reconfiugre it.  this usually clears up the issue, which can sometimes be a result of the update not fully intergrating into the existing configuration. 

I tried that and it didn't work...still won't save the device name changes. :(

@Harpo 

It sounds like you are trying to change the DHCP name.  If that is the case what is likely happening is when your device refreshes its DHCP lease it reaquires the device name from the device itself thus reseting the change.  Really the only way to solve this is to manually change the device name on said device, For instance your phone's name.  This will allow the router to aquire the name the next time the lease renews.  

Best Regards