Network service
Pi-hole on Synology: Docker Compose, DNS Ports and Reliability
Pi-hole is computationally light, but it occupies one of the most important roles on the home network: DNS. The official Pi-hole Docker documentation provides a Compose workflow and maps TCP/UDP port 53, which means a Synology deployment must reconcile DNS ports, DSM services, container networking and what happens when the NAS is unavailable.
Quick answer
The hard part is not CPU; it is network dependency
A Pi-hole container can run comfortably on modest hardware, yet a rebooting DiskStation can make clients appear to lose Internet access if it is their only configured DNS resolver.
Live Amazon products
Hardware relevant to this technical workflow
This Sprint 9F catalogue is intentionally focused on current and previous Synology Plus systems. Storage-repair pages can also read compatible third-party NAS hard-drive data from Cloudzat Storage Price Intelligence in read-only mode. Product cards support the decision; they never override current Synology compatibility or model-specific repair rules.
Technical decision
Design DNS failover before deployment
Use persistent configuration, document router settings and decide whether a second resolver will preserve name resolution during NAS maintenance.
Interactive technical tool
Pi-hole on Synology Deployment Checker
Use this as a planning aid. It identifies capacity, redundancy, deployment or repair constraints, but it does not replace the current Synology model manual, DSM documentation or upstream application release notes.
Technical safety checklist
Four checks before changing a production NAS
Protect data before maintenance
A healthy RAID state is not a backup. Confirm an independent restorable copy before repairs, DSM upgrades, RAID migration or major container changes.
Change one layer at a time
Storage, DSM, networking and application changes should be separated so an unexpected result can be traced to one action rather than several.
Record the exact state
Write down model, DSM build, pool type, drive serials, ports, mapped folders and current application versions before modifying a production NAS.
Verify the result
A repair or upgrade is complete only after storage health, services, backups and representative restores behave as expected.
Port 53 is the critical resource
Port 53 is the critical resource is central to Pi-hole DNS Service: Pi-hole’s Docker configuration publishes DNS on TCP and UDP port 53, so that host port must be free and reachable from client networks. For Pi-hole DNS Service, record the dns-resolver path baseline before action. When checking port 53 is the critical resource, compare the dns-resolver path result with that earlier dns-resolver path baseline.
A tested backup protects the dns-resolver path workflow during port 53 is the critical resource. For Pi-hole DNS Service, recovery of the dns-resolver path state matters more than speed.
Compose makes the deployment reproducible
For Pi-hole DNS Service, compose makes the deployment reproducible matters because the official project publishes a docker-compose example that maps DNS, web ports, environment settings and persistent directories. For Pi-hole DNS Service, record the dns-resolver path baseline before action. When checking compose makes the deployment reproducible, compare the dns-resolver path result with that earlier dns-resolver path baseline.
Document the dns-resolver path decision around compose makes the deployment reproducible. In Pi-hole DNS Service, record why the dns-resolver path state changed and what outcome the dns-resolver path procedure expects.
Persistent configuration survives image replacement
Inside Pi-hole DNS Service, the practical constraint is this: the Pi-hole configuration directory should be mapped outside the container so upgrades do not erase lists and settings. For Pi-hole DNS Service, record the dns-resolver path baseline before action. When checking persistent configuration survives image replacement, compare the dns-resolver path result with that earlier dns-resolver path baseline.
Keep persistent configuration survives image replacement separate from other dns-resolver path changes. On Pi-hole DNS Service, isolating the dns-resolver path work makes a failure in the dns-resolver path path easier to identify.
Router DNS settings determine who uses Pi-hole
The Pi-hole DNS Service reason to study router dns settings determine who uses pi-hole is straightforward: running the container does nothing for clients until DHCP, router or device DNS configuration points queries toward it. For Pi-hole DNS Service, record the dns-resolver path baseline before action. When checking router dns settings determine who uses pi-hole, compare the dns-resolver path result with that earlier dns-resolver path baseline.
Before buying hardware for router dns settings determine who uses pi-hole, decide whether the dns-resolver path target is capacity, redundancy or availability; verify the resulting dns-resolver path outcome directly.
A single DNS server is a failure dependency
Pi-hole DNS Service planning can fail here because if the NAS reboots and clients have no alternate working resolver, ordinary websites can appear offline even though the Internet connection is healthy. For Pi-hole DNS Service, record the dns-resolver path baseline before action. When checking a single dns server is a failure dependency, compare the dns-resolver path result with that earlier dns-resolver path baseline.
In Pi-hole DNS Service, make the dns-resolver path step reversible. Back up the dns-resolver path state; change one variable for a single dns server is a failure dependency; verify the dns-resolver path result before continuing.
Host and bridge networking behave differently
A safer Pi-hole DNS Service interpretation starts with one fact: DHCP, multicast and DNS reachability can change with the selected Docker network mode, so follow the official Pi-hole Docker networking guidance for advanced cases. For Pi-hole DNS Service, record the dns-resolver path baseline before action. When checking host and bridge networking behave differently, compare the dns-resolver path result with that earlier dns-resolver path baseline.
If a tutorial conflicts with the dns-resolver path behavior on Pi-hole DNS Service, stop at host and bridge networking behave differently; follow the model-specific Synology instructions for the dns-resolver path condition.
Web interface ports can be remapped
Web interface ports can be remapped is central to Pi-hole DNS Service: if DSM or another container already uses a common HTTP/HTTPS port, Pi-hole’s web management mapping can be moved without changing DNS port 53. For Pi-hole DNS Service, record the dns-resolver path baseline before action. When checking web interface ports can be remapped, compare the dns-resolver path result with that earlier dns-resolver path baseline.
A tested backup protects the dns-resolver path workflow during web interface ports can be remapped. For Pi-hole DNS Service, recovery of the dns-resolver path state matters more than speed.
DHCP mode adds more responsibility
For Pi-hole DNS Service, dhcp mode adds more responsibility matters because using Pi-hole as a DHCP server requires additional capabilities and network reachability beyond the normal DNS-only deployment. For Pi-hole DNS Service, record the dns-resolver path baseline before action. When checking dhcp mode adds more responsibility, compare the dns-resolver path result with that earlier dns-resolver path baseline.
Document the dns-resolver path decision around dhcp mode adds more responsibility. In Pi-hole DNS Service, record why the dns-resolver path state changed and what outcome the dns-resolver path procedure expects.
Updates should preserve configuration
Inside Pi-hole DNS Service, the practical constraint is this: the container image can be replaced during upgrades while mapped persistent directories retain state; read release notes for behavior changes. For Pi-hole DNS Service, record the dns-resolver path baseline before action. When checking updates should preserve configuration, compare the dns-resolver path result with that earlier dns-resolver path baseline.
Keep updates should preserve configuration separate from other dns-resolver path changes. On Pi-hole DNS Service, isolating the dns-resolver path work makes a failure in the dns-resolver path path easier to identify.
Query logs are sensitive data
The Pi-hole DNS Service reason to study query logs are sensitive data is straightforward: DNS history can reveal browsing and device behavior, so access to the admin interface and backups should be treated accordingly. For Pi-hole DNS Service, record the dns-resolver path baseline before action. When checking query logs are sensitive data, compare the dns-resolver path result with that earlier dns-resolver path baseline.
Before buying hardware for query logs are sensitive data, decide whether the dns-resolver path target is capacity, redundancy or availability; verify the resulting dns-resolver path outcome directly.
The NAS firewall can block a correct container
Pi-hole DNS Service planning can fail here because allow the required DNS traffic from intended subnets without opening the service unnecessarily to untrusted networks. For Pi-hole DNS Service, record the dns-resolver path baseline before action. When checking the nas firewall can block a correct container, compare the dns-resolver path result with that earlier dns-resolver path baseline.
In Pi-hole DNS Service, make the dns-resolver path step reversible. Back up the dns-resolver path state; change one variable for the nas firewall can block a correct container; verify the dns-resolver path result before continuing.
Redundant DNS makes maintenance boring
A safer Pi-hole DNS Service interpretation starts with one fact: a second Pi-hole or intentionally chosen fallback resolver prevents a storage reboot from becoming a household connectivity emergency. For Pi-hole DNS Service, record the dns-resolver path baseline before action. When checking redundant dns makes maintenance boring, compare the dns-resolver path result with that earlier dns-resolver path baseline.
If a tutorial conflicts with the dns-resolver path behavior on Pi-hole DNS Service, stop at redundant dns makes maintenance boring; follow the model-specific Synology instructions for the dns-resolver path condition.
Questions people ask
Pi-hole DNS Service: common questions
Can Pi-hole run on Synology?
Yes, Pi-hole publishes an official Docker image and Compose example that can be adapted to Synology Container Manager.
For Pi-hole DNS Service, "Can Pi-hole run on Synology?" depends on the dns-resolver path: check the exact DSM build for the dns-resolver path, the NAS model, and the current dns-resolver path state.
What ports does Pi-hole need?
DNS uses TCP and UDP port 53. The web interface also uses HTTP/HTTPS ports that can be remapped.
For Pi-hole DNS Service, "What ports does Pi-hole need?" depends on the dns-resolver path: check the exact DSM build for the dns-resolver path, the NAS model, and the current dns-resolver path state.
Can Pi-hole use bridge networking?
Yes in many DNS-only deployments, while DHCP and some advanced networking scenarios may need different network choices.
For Pi-hole DNS Service, "Can Pi-hole use bridge networking?" depends on the dns-resolver path: check the exact DSM build for the dns-resolver path, the NAS model, and the current dns-resolver path state.
Why does Pi-hole conflict with Synology ports?
DSM or other services may already bind a host port. Change web mappings where possible, but DNS still needs port 53 for normal service.
For Pi-hole DNS Service, "Why does Pi-hole conflict with Synology ports?" depends on the dns-resolver path: check the exact DSM build for the dns-resolver path, the NAS model, and the current dns-resolver path state.
What happens when the NAS reboots?
If Pi-hole is the only DNS resolver, clients may lose name resolution until it returns.
For Pi-hole DNS Service, "What happens when the NAS reboots?" depends on the dns-resolver path: check the exact DSM build for the dns-resolver path, the NAS model, and the current dns-resolver path state.
Should I use a second Pi-hole?
Redundant DNS is useful when you want name resolution to continue during NAS updates or failures.
For Pi-hole DNS Service, "Should I use a second Pi-hole?" depends on the dns-resolver path: check the exact DSM build for the dns-resolver path, the NAS model, and the current dns-resolver path state.
Does Pi-hole need much CPU?
The service is generally lightweight; network design and availability are usually more important.
For Pi-hole DNS Service, "Does Pi-hole need much CPU?" depends on the dns-resolver path: check the exact DSM build for the dns-resolver path, the NAS model, and the current dns-resolver path state.
Can Pi-hole provide DHCP on Synology?
It can in Docker with the appropriate capabilities and network design, but that is more complex than DNS-only use.
For Pi-hole DNS Service, "Can Pi-hole provide DHCP on Synology?" depends on the dns-resolver path: check the exact DSM build for the dns-resolver path, the NAS model, and the current dns-resolver path state.
How do I back up Pi-hole?
Protect its persistent mapped configuration and document router/DHCP settings needed to restore service.
For Pi-hole DNS Service, "How do I back up Pi-hole?" depends on the dns-resolver path: check the exact DSM build for the dns-resolver path, the NAS model, and the current dns-resolver path state.
Should Pi-hole be publicly accessible?
No normal home DNS deployment requires exposing port 53 to the public Internet.
For Pi-hole DNS Service, "Should Pi-hole be publicly accessible?" depends on the dns-resolver path: check the exact DSM build for the dns-resolver path, the NAS model, and the current dns-resolver path state.
Official references and methodology
Verify the exact model, DSM build and application state
This Pi-hole DNS Service guide uses primary documentation for the dns-resolver path. Cloudzat evaluates the dns-resolver path capacity, redundancy, deployment and recovery layers separately. Interactive dns-resolver path results support planning; final dns-resolver path changes need exact model guidance and current upstream documentation.
- Pi-hole: Docker deployment
- Pi-hole: Docker configuration
- Synology Container Manager: Projects and Docker Compose
As an Amazon Associate, Cloudzat may earn from qualifying purchases. Prices, NAS models, drive compatibility, DSM behavior and upstream application requirements can change. Verify the exact DiskStation model, current DSM documentation and application release notes before changing storage pools, replacing drives, exposing network services or upgrading production containers.