What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
If read-only connections are not spreading across your SQL Server Always On availability group (AG) secondaries, check the primary replica’s READ_ONLY_ROUTING_LIST first. The replicas meant to share connections must be grouped with an extra level of parentheses, such as (('Secondary1','Secondary2'),'Secondary3'). The nested group marks the load-balanced set; an ordinary flat list does not.
Why aren’t my AG secondaries load balancing?
SQL Server read-only routing sends qualifying read-intent client connections, addressed to an AG listener, to an available readable secondary. Load balancing applies to connection requests across the configured replica group—not to individual queries, and it does not guarantee equal CPU use, throughput, or workload.
Microsoft documents read-intent load balancing beginning with SQL Server 2016 (13.x). The syntax shown here is from Microsoft Learn’s SQL Server 2025 (17.x) documentation view; check the documentation for the SQL Server version you have deployed.
How the routing configuration fits together
Routing requires both destination information and a list of eligible destinations. Configure a READ_ONLY_ROUTING_URL for each replica that may receive routed connections when it is secondary. Configure a READ_ONLY_ROUTING_LIST on each replica that may become primary. Microsoft advises setting a replica’s routing URL before configuring the routing list.
#1 Best Overall
- 【Five Gigabit Ports】1 Gigabit WAN Port plus 2 Gigabit WAN/LAN Ports plus 2 Gigabit LAN Port. Up to 3 WAN ports optimize bandwidth usage through one device.
- 【One USB WAN Port】Mobile broadband via 4G/3G modem is supported for WAN backup by connecting to the USB port. For complete list of compatible 4G/3G modems, please visit TP-Link website.
- 【Abundant Security Features】Advanced firewall policies, DoS defense, IP/MAC/URL filtering, speed test and more security functions protect your network and data.
- 【Highly Secure VPN】Supports up to 20× LAN-to-LAN IPsec, 16× OpenVPN, 16× L2TP, and 16× PPTP VPN connections.
- Security - SPI Firewall, VPN Pass through, FTP/H.323/PPTP/SIP/IPsec ALG, DoS Defence, Ping of Death and Local Management. Standards and Protocols IEEE 802.3, 802.3u, 802.3ab, IEEE 802.3x, IEEE 802.1q
To designate replicas that should share read-intent connections, group them with nested parentheses in the primary-role routing list. In this example, Secondary1 and Secondary2 form the load-balanced group; Secondary3 is a fallback in routing-list order:
READ_ONLY_ROUTING_LIST = (('Secondary1','Secondary2'), 'Secondary3')Include only eligible readable secondaries with routing URLs. If the current replica is included as a fallback, Microsoft recommends placing it last.
Rank #2
- 【Flexible Port Configuration】1 2.5Gigabit WAN Port + 1 2.5Gigabit WAN/LAN Ports + 4 Gigabit WAN/LAN Port + 1 Gigabit SFP WAN/LAN Port + 1 USB 2.0 Port (Supports USB storage and LTE backup with LTE dongle) provide high-bandwidth aggregation connectivity.
- 【High-Performace Network Capacity】Maximum number of concurrent sessions – 500,000. Maximum number of clients – 1000+.
- 【Cloud Access】Remote Cloud access and Omada app brings centralized cloud management of the whole network from different sites—all controlled from a single interface anywhere, anytime.
- 【Highly Secure VPN】Supports up to 100× LAN-to-LAN IPsec, 66× OpenVPN, 60× L2TP, and 60× PPTP VPN connections.
- 【5 Years Warranty】Backed by our 5-years warranty and free technical support from 6am to 6pm PST Monday to Fridays
Check the full path from client to secondary
- Confirm the AG has a listener. The client must connect through the availability group listener, not directly to a replica.
- Confirm a destination can accept connections. At least one secondary must be configured to allow read-only connections.
- Check routing URLs. On each relevant replica, verify
READ_ONLY_ROUTING_URLis set for its secondary role. - Check routing lists for every possible primary. Each replica that may become primary needs the correct primary-role list, including the nested group for replicas meant to share connections.
- Check the client connection. The client must use TCP, specify a database in the AG, set
ApplicationIntent=ReadOnly, and use a provider that supports that property. Microsoft recommendsMultiSubnetFailover=True; for distributed network name listeners, its troubleshooting guidance also calls out provider support for that option. - Check the destinations and listener state. Verify the listed instances host readable secondaries, their access settings permit read-only connections, their routing URLs are correct, and the listener is online.
Inspect replica settings and the routing list
Use this query to inspect replica access settings and routing URLs:
Quick wins for a faster PC:
Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →SELECT replica_id,
replica_server_name,
secondary_role_allow_connections_desc,
read_only_routing_url
FROM sys.availability_replicas;To inspect the configured routing-list entries, query sys.availability_read_only_routing_lists. These catalog checks can reveal configuration mismatches, but they do not verify that a client supplied read-only intent or prove that connections are evenly distributed.
Rank #3
- 【Flexible Port Configuration】1 Gigabit SFP WAN Port + 1 Gigabit WAN Port + 2 Gigabit WAN/LAN Ports plus1 Gigabit LAN Port. Up to four WAN ports optimize bandwidth usage through one device.
- 【Increased Network Capacity】Maximum number of associated client devices – 150,000. Maximum number of clients – Up to 700.
- 【Integrated into Omada SDN】Omada’s Software Defined Networking (SDN) platform integrates network devices including gateways, access points & switches with multiple control options offered – Omada Hardware controller, Omada Software Controller or Omada cloud-based controller(Contact TP-Link for Cloud-Based Controller Plan Details). Standalone mode also applies.
- 【Cloud Access】Remote Cloud access and Omada app brings centralized cloud management of the whole network from different sites—all controlled from a single interface anywhere, anytime.
- 【SDN Compatibility】For SDN usage, make sure your devices/controllers are either equipped with or can be upgraded to SDN version. SDN controllers work only with SDN Gateways, Access Points & Switches. Non-SDN controllers work only with non-SDN APs. For devices that are compatible with SDN firmware, please visit TP-Link website.
What the fix does—and does not do
Microsoft describes read-scale forwarding in round-robin terms. The configuration controls where qualifying connection requests can be routed; it is not a scheduler for individual queries or a promise that each replica will receive the same amount of work. Readable secondaries alone are not enough: the listener, primary’s routing list, destination URLs and access settings, and client intent all need to line up.
Quick Recap
Best Value
- Multi-WAN Business Continuity: Connect up to 5 ISPs with automatic failover and load balancing — if one connection drops, traffic instantly reroutes to keep your business, remote office, or home lab online
- OpenWRT-Ready Enterprise Control: Full OpenWRT support unlocks VLAN segmentation, advanced firewall rules, custom QoS policies, and community-developed packages for professional-grade network management
- Complete VPN Gateway Suite: WireGuard, OpenVPN, IPsec, PPTP, and L2TP server and client built in; create site-to-site tunnels, host remote access, or route specific VLANs through encrypted VPN connections
- Professional Security Stack: SPI firewall, DoS attack prevention, IP/MAC binding, domain filtering, and DMZ hosting protect your network perimeter while keeping critical services accessible
- Flexible Deployment & Monitoring: Web GUI or Cudy App cloud management with TR-069 support; built-in diagnostic tools (Ping, Traceroute, NSLookup, system logs) for rapid troubleshooting anytime
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
