resolve the hostname which set in the dhcp static leases and do not force the gateway to be configured

### Prerequisites

Please answer the following questions for yourself before submitting an issue. **YOU MAY DELETE THE PREREQUISITES SECTION.**

- [x] I am running the latest version
- [x] I checked the documentation and found no answer
- [ ] I checked to make sure that this issue has not already been filed

### Problem Description
* First of all, thank you for all the hard work on this great product.
* Recently I use the ADH dhcp feature in my local network, and I have set some dhcp static leases, but I found that I can not resolve the hostname which I set in the dhcp static lease with the ADH dns feature, and It seems that no documentation mentions configuration instructions in this regard
* And the second feature which I want is, in some time, I do not wish the dhcp server to send me a default route, can this restriction on setting the gateway address be removed?

### Additional Information
#### related screenshoots