Is My ISP Throttling My Internet?
ISP throttling — deliberately slowing specific traffic — is real and more common than most users realise. Here's how to detect it and what you can do about it.
The telltale sign
Netflix or YouTube buffer slowly, but a speed test shows full speed. Specific services are affected while others aren't. Speeds recover when you connect through a VPN.
How to confirm it
Run a speed test normally, then run one through a VPN. If VPN speed is significantly higher for affected services, throttling is likely.
What is ISP throttling?
Throttling is when your Internet Service Provider deliberately limits the speed of specific types of traffic or specific destinations. It differs from general congestion — throttling is intentional and targeted, while congestion affects all traffic equally at peak times.
Common throttled traffic types:
- Video streaming — Netflix, YouTube, BBC iPlayer, Disney+ are frequently throttled on some ISPs
- Peer-to-peer (P2P) / torrents — almost universally limited on ISPs worldwide
- VoIP and video calls — occasionally throttled to protect the ISP's own phone services
- Gaming traffic — less common, but reported on congested networks
How to detect throttling: the VPN test
- Note which service is slow (e.g. Netflix buffering, YouTube stuck at 360p)
- Run a speed test without a VPN — note your result
- Connect to a VPN server (free options: ProtonVPN, Windscribe; or any paid VPN you have)
- Run the same speed test again through the VPN
- Try the slow service again with the VPN connected
Result interpretation:
- VPN speed test is higher AND the slow service works better → throttling is likely
- VPN speed test is lower (this is normal, VPNs add overhead) AND slow service is no better → not throttling, something else
- All speeds are the same regardless of VPN → almost certainly not throttling
How to detect throttling: the time-of-day test
General congestion (not throttling) gets worse at peak hours (evenings) and recovers overnight. Throttling is typically consistent at all hours.
- Run speed tests at 6 AM, 12 PM, and 8 PM for several days
- Save results — create a free account to store them automatically
- If speed is consistently low at all hours on a specific service but fine for others, that points to throttling rather than congestion
Throttling vs congestion — key differences
| Factor | Throttling | Congestion |
|---|---|---|
| Time of day | Consistent all day | Worse evenings, better mornings |
| Services affected | Specific (Netflix but not YouTube) | All traffic equally slower |
| Speed test result | Often shows full speed | Lower speed at peak hours |
| VPN effect | Service improves with VPN | VPN makes no difference |
What to do if you confirm throttling
Option 1: Contact your ISP
Call or email your ISP with your documented evidence — speed test results at different times, before/after VPN comparisons. Ask specifically about "traffic management policies" for the affected services. ISPs in many countries (UK, EU, US) are legally required to disclose traffic management practices. In the UK, Ofcom's General Conditions require ISPs to disclose shaping policies on their website or to customers on request.
Option 2: Use a VPN for affected services
A VPN encrypts all traffic, preventing your ISP from identifying what type of data you're sending. This prevents service-specific throttling. However, VPNs add overhead — choose one with WireGuard protocol and a server in your country to minimise the speed impact. Note that VPNs won't help with ISP congestion (which affects all traffic equally).
Option 3: Upgrade your plan or switch ISPs
Some ISPs only throttle traffic on budget or unlimited plans. Upgrading to a higher tier may remove throttling. If the throttling is on all plans, switching providers is the most effective long-term solution. Compare providers using our ISP rankings →
Speed tests and throttling
Some ISPs detect when you're running a speed test and temporarily give your connection full speed to show better results. This is one reason why test-based evidence can be tricky to use. To work around this: use multiple testing tools, test at different times, and specifically test the services that feel slow rather than relying solely on speed tests.