Local network vs ISP speed: what really caps your broadband

Local network vs ISP speed comes down to two separate bottlenecks: the speed your provider delivers to the front of your house, and the speed your own router, Ethernet ports and Wi-Fi can carry once it is inside. Your real-world broadband speed is whichever of those two is lower, so a 2Gbps line running through a 1Gbps Ethernet port will never test above about 1Gbps on a single device.

For a heavy user gaming, streaming and working from home, this matters more than the headline package speed. You can pay for full fibre and still see disappointing speed tests if your local kit, cabling or Wi-Fi is the limit rather than the line. This explainer sets out exactly where speed is lost, how to tell whether the problem is your line or your home network, and why advertised “average” speeds rarely match what you see. Free Price Compare draws on published Ofcom, ASA and industry data to keep the figures current and UK-specific.

Last updated: July 2026

Written by the Free Price Compare editorial team | Reviewed July 2026

Where is your broadband speed actually lost?

Broadband speed is lost at two points: on the ISP feed reaching your property, and on your local home network once the signal is inside. Your real-world broadband speed is always whichever of these two is slower, never the higher of the two. If your provider delivers 1Gbps to the door but your Wi-Fi only carries 300Mbps to your laptop, you will see around 300Mbps.

The ISP side covers the technology and network between the exchange and your home. Full fibre (FTTP) runs fibre optic cable all the way to the premises and can reach 1Gbps or more, while older FTTC part-fibre lines typically deliver around 30 to 70Mbps because the final stretch is copper. ADSL is slower again, at roughly 8 to 24Mbps depending on distance from the exchange.

The local side is everything you own: the router, the Ethernet cables and ports, and the Wi-Fi radios. A modern router such as Virgin Media’s Hub 5 pairs Wi-Fi 6 with one 2.5Gbps and three 1Gbps Ethernet ports; its full fibre Hub 5x adds a 10Gbps port for XGS-PON service. Those port speeds set a hard ceiling on any single wired device, regardless of what the line can carry.

[STAT NEEDED: Ofcom, Ofgem, ABI, FCA or ONS]

Is Ethernet faster than WiFi?

Ethernet is faster and more consistent than Wi-Fi for most home connections because a wired link carries the full port speed with almost no interference or distance loss. A wired device gets a stable connection straight to the router, while Wi-Fi shares the air with walls, other devices and neighbouring networks that all reduce throughput.

The important caveat for heavy users is the Ethernet port and cable rating. Standard Gigabit Ethernet caps a single wired device at 1Gbps, so if you pay for a 2Gbps line and plug into a 1Gbps port, that device is limited to around 1Gbps no matter what. Older or damaged cables can drop a link to 100Mbps, which is a common cause of a wired device stuck near 95Mbps while the line itself is far faster.

For gaming and video calls, the bigger win from Ethernet is not raw speed but lower latency and steadier performance. A wired connection avoids the packet loss and lag spikes that make Wi-Fi feel unreliable during peak evening use.

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Why is my WiFi slower than my broadband speed?

Your Wi-Fi is slower than your broadband line because the wireless signal loses speed travelling through the air, through walls and across multiple connected devices, so it rarely delivers the full speed reaching your router. This is normal: a speed test over Wi-Fi measures your local wireless link, not the ISP line, so a 900Mbps line can easily test at 400 to 600Mbps over Wi-Fi.

Several factors reduce Wi-Fi speed inside a UK home. According to the Advertising Standards Authority, the speed you get depends on where you live, the technology your provider uses, how many people are online at once and what they are doing, such as streaming. Distance from the router, thick walls, the 2.4GHz versus 5GHz band and congestion from neighbouring networks all cut throughput further.

• Test on the 5GHz band close to the router, then again far away, to see how much distance costs you.
• Run a wired test into a 1Gbps or faster port to reveal the true line speed with Wi-Fi taken out of the equation.
• Check whether an old router only supports Wi-Fi 5; upgrading to a Wi-Fi 6 router or adding mesh units helps cover a whole home.

If you rely on Wi-Fi across a larger property, our guide to improving broadband speeds covers mesh systems, router placement and wired backhaul in more detail.

Why is the advertised “average” speed not your speed?

Advertised broadband speeds in the UK only have to be achievable by at least 50% of a provider’s relevant customers at peak time, defined by Ofcom as between 8pm and 10pm. This rule, set by the ASA and Committee of Advertising Practice, has been in force since 23 May 2018 and replaced the older “up to” claims that only 10% of customers needed to reach.

The practical effect is that an “average” figure in an advert is a median across half the customer base at the busiest time of night, not a promise for your line. Where you live, your line technology and evening congestion can all leave you below that average. Providers must state the figure as an “average” speed and are encouraged to promote speed checkers so you can estimate your own line.

Separately, the Ofcom Broadband Speeds Code of Practice requires providers to give you a personal maximum speed estimate at the point of sale, usually as an upper and lower range. If your speed falls too far below that estimate and the provider cannot fix it, you can often leave the contract without penalty. If you think your speed is persistently short of what was promised, our guide on complaining about broadband speed explains your rights.

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Why do upload speed and reliability matter more for heavy users?

Upload speed is the amount of data your connection can send outward, and it is not covered by the advertised-average rule, which only applies to download speed, so it is easy to overlook when comparing packages. For anyone working from home, uploading large files, backing up to the cloud or streaming their own video, upload is often the real bottleneck rather than download.

Full fibre (FTTP) is where upload speed changes most. FTTP connections frequently offer symmetric or near-symmetric speeds, so upload matches or approaches download, unlike the asymmetric FTTC and cable connections most UK homes have used, where upload is a small fraction of download. Ofcom’s data underlines how much heavy users lean on their lines: average data usage reached 583GB per connection in July 2025, up 10% year on year, and full fibre connections averaged around 738GB, almost 30% more than the overall figure.

Reliability is the other factor headline speed hides. A steady connection with low latency and no evening slowdown is worth more to a gamer or remote worker than a bigger download number that drops during peak hours. When you compare, look at the guaranteed minimum speed, the upload figure and the connection type, not just the advertised download.

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How can you test whether it’s your line or your home network?

To find out whether slow speed is your ISP line or your home network, run a wired speed test straight into the router, then compare it with a Wi-Fi test in the same spot. A wired result close to your package speed points to a Wi-Fi or in-home problem; a wired result well below the package speed points to the line or the ISP side.

• Plug a computer into a 1Gbps or faster router port with a Cat5e or Cat6 cable and run a speed test; this removes Wi-Fi from the result.
• If the wired test is close to your plan speed but Wi-Fi is far lower, the issue is the wireless network: try 5GHz, move closer, or add mesh coverage.
• If the wired test is stuck near a round number such as 100Mbps or is far below your plan, suspect a faulty cable, a slow port, or an ISP-side limit worth reporting to your provider.
• Test more than one device; a single slow laptop while others are fast usually means that device’s network card or drivers, not the line.

Where the line underperforms your provider’s point-of-sale estimate, that is when the Code of Practice and, in some cases, a penalty-free exit come into play. UK coverage is now broad enough that most homes have a faster option available: gigabit-capable networks reached 87% of UK premises by late 2025 (Ofcom Connected Nations 2025), and independent tracking from thinkbroadband put gigabit availability above 90% by mid-2026.

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What are the typical real-world speeds by broadband technology?

Broadband technology is the type of line connecting your home to the network, and it sets the ceiling on the speed your ISP can deliver, before your home network even comes into play. Full fibre gives the highest and most consistent speeds because the fibre runs all the way to your home, while part-fibre and copper lines lose speed over the final distance.

Figures are indicative and may change. Full fibre availability reached 78% of UK residential premises in 2025 (Ofcom Connected Nations 2025), so a symmetric-upload FTTP option is now within reach for most households. If your current line is FTTC or cable and upload matters to you, moving to FTTP is usually the single biggest real-world improvement, ahead of any local network upgrade.

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Information correct as of 4 July 2026. Prices, tariffs, policy details and providers change frequently, so please check the latest details before making a decision. This article is for general information only and does not constitute financial advice. Free Price Compare is authorised and regulated by the Financial Conduct Authority (FCA).