Friday, Sep 22, 2023

How to Troubleshoot Network Slowdowns


A functioning network doesn’t always mean the network is working correctly. In fact, if your network is “up” but has intermittent issues, it can be even more frustrating and is likely to negatively impact business productivity. Choppy VoIP audio, lagging video calls, and application slowness are all network-related problems, which can drastically bring down office productivity. Therefore, it is critical to quickly identify and remedy network problems so that your office can function at the highest efficiency and with minimal downtime.

In this blog post, we share tips to help you troubleshoot network slowdowns and performance issues quickly and efficiently.

Tips For Troubleshooting Network Slowdowns

There are a large number of variables in a network that can cause slowdowns and inefficiencies. The type and design of the network, traffic volume, and peak of network traffic, network hardware, etc. can result in occasional slowdowns. However, if the network slowdowns and bottlenecks occur consistently, you will need to pinpoint the location of the problem. 

To help you locate network issues quickly, we have listed some of the most common causes of network slowdowns and inefficiencies as well as some tips for troubleshooting in the following sections.

1. Issues With Network Interface Cards

Malfunctioning network interface cards (NICs) are often the culprits behind network slowdowns. In fact, they are known to even bring the entire network down. Faulty network adapters sometimes broadcast useless data packets onto the network. This is referred to as “junk-spitting”. Such junk traffic when broadcast in a domain can interfere with and cause slowdowns in other devices in the same broadcast domain.



If you notice any switch port with a solid light, it indicates that it is sending out constant traffic and that will point you to the offending NIC. Another way to detect faulty NIC is by using the Ping command. The point at which the data packets sent by the ping command stops will be the device with the faulty NIC. Once you disconnect the faulty NIC, your network performance should immediately improve.

However, in large networks with hundreds or thousands of devices, this approach isn’t practical. Luckily there are many network monitoring software available that can detect such issues and tell you the MAC address of the faulty NIC. You can also use a packet sniffer or similar network solutions to troubleshoot network slowdowns.

2. Poor Cabling

Solid underlying network cabling is essential for a healthy network. Poor cabling jobs can lead to a host of network problems including network slowdowns. Networks nowadays run at 1,000 Mbps or even at Gbps. So the design of your cabling must be able to support such speeds. The quality of the cabling job is also an important factor in network performance. Improperly crimped cable ends, loose ends, incorrect types of connections result in network slowdowns.



Statistics on the network equipment can help you locate bad patch cables. Excessive Cyclic Redundancy Check (CRC) errors on a given port are indicative of faulty cabling. Once the faulty cable is located, you can replace it to see if that fixes the problem. You can also use the Ping and Traceroute utilities to locate network problems. Ping sends packets to a network device, which then responds with a reply if it is active. It also reports the time it takes for a particular device to respond. Traceroute serves a similar function but it tracks the entire network path. These two utilities are invaluable in locating network issues and bottlenecks.

Specialized hardware tools called network cable testers that help you pinpoint and correct cable-related network problems are also readily available. These tools can test the network cable for continuity, shorted pairs, and crossed pairs. They can also determine the length of the cable as well as how far down the cable the fault is located. Such tools are very useful in expediting network cable repairs.

3. Failing Switches, Routers, Or Access Points

Network equipment such as routers, switches, and access points have a serviceable life of around three years. You can use them for up to five years but they will start showing their age during the last couple of years. Data-heavy network operations can also force frequent maintenance or updates.



Around ten years ago, 802.11n was the top-of-the-line local area network (LAN) technical standard with speeds of around 450 megabits per second (Mbps). However, now the norm is 802.11ac, which offers top speeds in gigabits per second (Gbps). That’s a huge difference in speed. Delaying the adoption of new technologies can leave your business behind while your competitors take the lead.

Inconsistent network performance is often an indicator of the age of the network equipment. For example, e-mail may function properly, but web traffic may stop working, the intranet may be working but external emails may not be reaching inboxes. In such cases, rebooting or power cycling one or the other network equipment often helps return the network to proper operation. But if you have to do this often, it indicates that your router, switch, and/or access points may be nearing their end of life and should be replaced.

4. DNS Errors

DNS (Domain Name System) configuration errors are a common source of network issues including slowdowns. DNS is critical for the proper functioning and performance of a TCP/IP network. Since DNS works hierarchically if one DNS server is misconfigured it will impact all of the network components connected to it. DNS protocols are not very complicated but can lead to a number of network issues related not just to performance but also to the integrity and security of the network.



Without a DNS server, systems may find it difficult to locate local resources, which may disrupt the communication between Windows systems and Active Directory. Also, systems without a local DNS server may experience delays or outages. Placing DNS servers close to the network systems solves a lot of such problems.

However, you need to ensure that the servers are configured correctly so that they enhance response times without putting greater demand on the network. It often happens that when you update DNS systems, some workstations or routing equipment don’t receive the updates. Therefore, you should ensure that all systems receive relevant updates and are configured to use the proper DNS servers.

5. Interference In The Wireless Network

Interference in the wireless network is a common source of network disruptions especially if your office is located in a densely populated area. Common kitchen equipment such as microwave ovens can impact your wireless network. Your neighbor’s Wi-Fi network can also interfere with your own network. Such interference is more prevalent when using the 2.4GHz band because it has a longer range.

Utilizing the dual bands 2.4GHz and 5GHz strategically is a good way to mitigate wireless interference. It is a good practice to use the 2.4GHz for IoT devices while reserving the 5GHz band for laptops. Additionally, since the 5GHz band has a shorter range, you can place access points more freely without the risk of interference from neighboring Wi-Fi networks in high-density areas. Also, most business-grade Wi-Fi equipment can broadcast both the 2.4GHz and 5GHz bands, automatically steering devices to the best band available.



6. NetBIOS Conflicts

NetBIOS (Network Basic Input/Output System) which was created in the early 1980s is still used especially on Windows NT 4.0 networks. It contains built-in processes that catch and manage network conflicts. However, these processes sometimes fail to handle the conflicts properly resulting in inaccessible file shares, increased congestion, and even network outages.

In addition, NetBIOS has many security concerns that can give attackers the ability to poison and spoof responses, obtain hashed credentials, and inspect web traffic, etc. So keeping it enabled is not always a good idea. If you can, it is recommended to disable NetBIOS on your network. Disabling the use of NetBIOS will not just prevent outages caused by failed conflict handling but also enhance your network security.

7. IP Conflicts

Normally Windows prevents two devices with the same IP address from logging on to a network. However, this can sometimes happen and when it does, it can cause network slowdowns and outages for the devices with the same IP address. For instance, an IP conflict may occur when one device receives an IP address automatically while another uses a static address specified by the user. To prevent IP address conflicts, ensure that there is no rogue DHCP server on your network, that there are no overlapping or duplicate entries in the configurations, and that machines with static IP addresses have been excluded from the DHCP pools.

8. Malware Infection

Despite employing robust network security measures sometimes malware does get through. Once malware infiltrates your network, it can hog resources, exfiltrate data, and cause network slowdowns. To prevent malware infection, you need to build layered security systems. 



Here are some steps for preventing network slowdowns due to malware infection:

  • Ensure that a firewall is deployed and configured correctly. 

  • Deploy anti-malware and antivirus software on all machines.

  • Ensure that devices have the latest updates and patches installed.

  • Implement effective end-user policies.

  • Provide phishing training for all employees.

9. Insufficient Bandwidth

Occasionally, networks can be overloaded with applications. For example, you have web-based user applications, VoIP, video streaming, video conferencing, and IoT devices in addition to regular email and web usage. Simultaneous and large demand on the network can slow it down if it doesn't have the required throughput.

To prevent unnecessary load on the network implement usage policies. You can also use hardware or software-based web filtering tools to prevent overwhelming the network. You can also allocate data pipes to manage VoIP voice and data traffic. However, sometimes even after exhausting all the available solutions the network slowdowns just don’t cease. In such cases, it may be necessary to upgrade your subscription from your Internet Service Provider (ISP).


Network slowdowns result in loss of business productivity and frustrated users. Sluggish network issues are some of the biggest challenges of any IT administrator. Preventing, diagnosing, and solving network problems is a lot easier if you are aware of the likely culprits. The common causes of network slowness that we have listed above will help you quickly narrow down your search and locate the network issue. Your ability to quickly detect and prevent network problems will help improve office productivity and facilitate the achievement of business goals.

Is your business suffering from frequent network slowdowns or outages? Are you paying for high bandwidth but not getting the expected speeds? Reach out to us by clicking the button below and our network experts will help you solve any and all of your network-related problems.

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By: Hari Subedi
Title: How To Troubleshoot Network Slowdowns
Sourced From:
Published Date: Thu, 08 Jul 2021 08:00:00 +0000

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