I recently subscribed to Telia’s mobile Internet service and bought ZTE MF286R 4G router they sell. The first thing I noticed, was the absence of DNS settings, which is a no-deal for me, because I use my home DNS server as a first line of defence against ads, spam, pr0nogrąphy, malware and other unwanted websites. Thankfully, this problem is easily solvable.
Pi-hole is my DNS server and it has an integrated DHCP server functionality (i. e. it can assign IP addresses to network devices). When you appoint it as DHCP server, Pi-hole will serve as DNS server too. To achieve this, firstly, turn-off DHCP functionality in the ZTE router settings (Advanced settings -> Router):
Secondly, turn-on DHCP server in the Pi-hole settings (fig. 2):