Synology DHCP Server 20 character limit

Hi had the same problem, so I made the necessary DHCP changes using the GUI and afterwards I connected to the diskstation (DS412+) using putty, logged in as root using the admin password.

Afterwards go to /etc/dhcpd, where you’ll find a number of files.

In my case I edited the dhcpd-bond0-bond00.conf and dhcpd.conf files and changed in both files the domain-search and domain-name strings to the desired value.

dhcp-option=tag:bond00,option:domain-search,www.yourdomain.xxx
dhcp-option=tag:bond00,option:domain-name,www.yourdomain.xxx

Afterwards I changed to /etc and used ./rc.network restart.

After this everything is running fine again

Hope this helps