It's a packet loss issue. Best thing to do is to run a ping plotter and see where the high ping is occurring. On my tests im getting high packet loss on hop 3 220.127.116.11. My download speed is dropping and im getting high jitter 100ms-200ms at times. Your not alone with this issue as me and another person on this forum have same issue. This points to the problem being in BT network
Has anyone with these issues tried to set the Ethernet port on their PC to have a fixed link speed rather than the default automatic negotiation? I have had past network issues with this feature, which is worse depending on the chipset used by the ethernet ports.
Just go into Windows Device Manager and select the network card. Click on the Advanced tab and find the item "Speed & Duplex". Change from "Auto Negotiation" to the maximum speed the device you are connecting to will support (e.g. 1.0 Gbps Full Duplex).
I was notified that this thread was necro'd so thought I'd restate the _actual_ fix for the OP, myself, and many others - anything else, such as laughably suggesting to use ethernet instead of wireless shows that they have not read this thread.
I switched to LLU and haven't had the problem since 🙂
Have a look through the forum - a few people - myself included - resolved this by changing ISP - if you are out of contract and there is capacity at your FTTC cabinet then there is no harm in trying, especially if you choose an ISP that does rolling month to month contracts (you'll even save yourself some money).
There is a lot of disinformation in this thread that shows a fundamental misunderstanding of networks, skewed in a light that is positive to BT - again, draw your own conclusions - if you didn't have this problem before, and now you magically do, think before accepting that the internet and its infrastructure, and the fundamentals of networks changed over night.
You may have a genuine problem, but if it is not evident from a basic line test BT wont fix it anyway as latency isn't in the SLA or T&C - but as they advertise FTTC as a gaming service you may get some mileage quoting the Consumer Rights Act 2015, as the product/service has been mis-sold and is not fit for purpose (google broadband consumer advice).
Search the forum, see the DRASTIC increase in this problem occurring since late last year and draw your own conclusions.
Latency spikes should only occur on a saturated connection that doesn't employ QoS or SQM, or if the service (or the route to that service) is under load and congested (very very rare).
I implemented several variants of QoS and bandwidth limitations to no avail, as even limiting the device bandwidth to 1Mbps down and 0.25Mbps up caused issues (again, that changing ISP fixed - without needing to throttle anything).
Always give BT a chance first though, there is a chance you have a fixable problem, but if you are one of the many that have tried for months to resolve this, you may find that the grass really is greener on the other side.
There are threads like this in other ISP forums, but at least they get resolved (congested VLANS etc) - do your own research before picking a new provider.