Hi all, hoping someone from BT can help as I've been going in circles with support for a while now.
I'm on BT Full Fibre 900 (900 down / 110 up) and have a consistent upload issue that I've now been able to narrow down quite specifically.
The problem:
Single TCP connection upload is capped at around 4-5mbps regardless of destination. Multi connection speed tests (Ookla default) show 30-40mbps upload which looks normal on the surface, which is why support keeps dismissing the issue.
My primary use case is streaming to platforms like Twitch. For a stable 1080p60 stream I need at least 6000kbps reliably. I am consistently unable to achieve this despite being on a 110mbps upload plan.
How I've confirmed this:
- Ookla in single connection mode: 4-5mbps upload
- Cloudflare speed test (single connection by design): 4-5mbps upload
- Twitchtest (a dedicated tool for testing upload speed directly to Twitch's ingest servers, eliminating streaming software from the equation) to Ireland and Paris: 1000-4000kbps, fluctuating
- YouTube upload: similarly poor
- All tests done wired, late at night when no other devices are active, ruling out local congestion
What I've already ruled out:
- WiFi: all testing wired
- Local network congestion: same results late at night as peak time
- Home networking equipment: switch and cabling all gigabit rated
- Streaming software: same results in OBS, Meld Studio, and confirmed independently via Twitchtest which bypasses streaming software entirely
- VPN routing: tested NordVPN and Surfshark across multiple server locations including London, Amsterdam and Paris, no improvement
- Bufferbloat: Waveform bufferbloat test returns an A grade with only +4ms upload latency increase under load
WinMTR trace findings:
- YouTube trace exits BT's network cleanly, reaches Google destination with 0% loss at 14ms latency
- Twitch ingest trace never visibly exits BT's network, runs out of hops without confirming delivery
- Both traces show identical behaviour through BT's own hops
What BT support has done so far:
- Multiple calls to support
- ONT replacement
- BT can see 90-97mbps at the hub on their end
- BT are not raising a fault as they consider everything perfectly healthy, pointing to the 10mbps minimum guarantee being met
Each time I call I am dismissed over the phone with no escalation to a technical team. When I try to relay my findings I am told it is going over the customer support agent's head. I have a 110mbps upload plan, being told it's 97 on the hub's end which is fine, and being told the minimum guarantee is 10mbps which I'm still not hitting.
My conclusion:
The gap between multi connection (30-40mbps) and single connection (4-5mbps) upload, consistent across every destination and unaffected by VPN, points to a fault in how my line is handling individual TCP connections rather than a routing or peering issue. This isn't something I can fix on my end.
Can anyone from BT advise how to get this properly escalated to a technical team who can look at the line configuration rather than just the headline speed figures?
