Is there no way to stop uploading a large file taking out my internet connection?

[d000hg]

I have a fairly standard Fibre connection 40/8Mbps or so. Uploading a large file we totally lost any sort of internet access for the duration - this isn't new but I hadn't done it for ages. It feels a bit like the dark ages, and it only happens with uploads - I can be downloading a file and still browse quite happily, it seems to automatically balance the two.
Remind me on a Fibre connection can I download and upload at 40/8 at once, or is it shared and each 1Mpbs upload effectively reduces my download by 5Mbps? I've tried putting limits on my router upload rate before without much luck... is there any obvious solution within the capacity I have or is this basically just how it is with Fibre?

[BigDataPro]

Latest routers allows/provides priority settings for each device. Devices can be configured individually. Not sure if your is the latest.

[Lance]

it's not how it should be. The FTTC links are duplex. So you have upload and download at the same time without impacting.



However.... Every packet sent will need a packet to be received (assuming TCP). You want the largest possible packets for the data transfer.
Check the MTU of the router. Around 1400 should be fine, but you could try lowering it to 1350 just to reduce an fragmentation.
Also try a different device as maybe your TCP window size on the device you're using is too small.

Run Wireshark to see what is going on with TCP window sizes and renegotiations and also see if there is much fragmentation.

Is the problem with uploads to anywhere?
Maybe try Filezilla as it has rate limiting as well as very good restart features.

[d000hg]

I've seen it generally, this was uploading a file to google drive. My router is a TP-Link Archer AR900 / AC1900 (https://www.amazon.co.uk/gp/product/B01N2LSLMH/) which while consumer grade at £100 back in 2018 should be several steps up from whatever the ISP gives you.
Seems my MTU is 1480 which is the default on this device. I'd have to check if I have a second device I can test a big upload from, my main machine is a 2012 Mac Mini though I know it happens regardless wired/wireless networking. Maybe I can get my phone to upload a big video to Youtube or something.

[Lance]

I've seen it generally, this was uploading a file to google drive. My router is a TP-Link Archer AR900 / AC1900 (https://www.amazon.co.uk/gp/product/B01N2LSLMH/) which while consumer grade at £100 back in 2018 should be several steps up from whatever the ISP gives you.
Seems my MTU is 1480 which is the default on this device. I'd have to check if I have a second device I can test a big upload from, my main machine is a 2012 Mac Mini though I know it happens regardless wired/wireless networking. Maybe I can get my phone to upload a big video to Youtube or something.

1480 is too high IMO. You'll get fragmentation. Drop it 1400 and try it.
Also try the ISP provided router. You might be surprised. They tend to make them robust for the common use cases. More expensive ones are OK for advanced features, but £100 is too cheap.

[d000hg]

1480 is too high IMO. You'll get fragmentation. Drop it 1400 and try it.
Also try the ISP provided router. You might be surprised. They tend to make them robust for the common use cases. More expensive ones are OK for advanced features, but £100 is too cheap.

I tried the ISP one it was dreadful. Been through several as they kept failing. Pretty sure mine has higher specs, you can pay £40 to basically get what the ISP provides. We're a house of 2...

I'll have a look at the MTU setting and do some tests.