[1.1.87] Map download speed slower since upgrading internet connection

[TheFluteGnome]

Hi,

My friends and I have been working our way through a Space Exploration save for a few months which I have been hosting as a headless client from a .zip version of 1.1.87.

This has been running quite happily with people joining the serving downloading the map at around 3MBps via my public address.

I have recently swapped from NowTV to Vodafone, from an FTTC to an FTTP connection, going from 60Mbps to 900Mbps download speed, and 20Mbps to 100Mbps upload speed. I was expecting this to either improve the download time, or quite honestly would have been happy if it stayed the same!

Sadly though, it's made the server unjoinable, as the map downloads at 400kBps. This is A) too slow for the map size we are working with and B) too slow to actually catch up if the server is running at the same time.

Has anyone else had a similar experience with this? What could be causing the slowdown? In my search I've come across a few other people complaining about Vodafones packet routing going all over the place, but currently I do seem to be connected to my local network centre and have been able to play other games with no particular latency issues.

Any thoughts appreciated!

[Loewchen]

Post server and client log of a session with the issue, see 52433.

[TheFluteGnome]

Thanks for the quick reply. I'm attaching 3 logs. One for the server, one from myself (who can connect) and one from my friend (who can't connect)

I am running a second 1.1.87 zip instance of the game as my client. If I join using my local IP, I can download at around 30MBps, presumably a read/write limit somewhere. That's plenty quick enough anyway! If I join using my public IP (as I did in these logs), via my DNS, I then download at around 8MBps, which is working fine.

The issue is when other people try to connect, also via my public IP. That's when they download at around 400kBps. In this instance, my friend was able to download the map but wasn't able to catch up to the server effectively and so quit out.

[Rseding91]

Typically failure to upload at decent speeds is due to the packet latency between the peer and the server and packet reliability. Reliability is normally not an issue, but if packet latency variance is high (called jitter) it causes a lot of issues with determining how fast the server should send data to the peer.

Do you have any way to measure packet jitter for your connection? A search shows a lot of websites that will offer tests, but I can't say for sure which one would work for testing in your location.

[TheFluteGnome]

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I'm not entirely sure what would count as a bad jitter in this case, but this seems reasonable. I have noticed my latency and packet loss will jump occasionaly when playing other games, but if that was the issue I'd only expect the map download rate on factorio to drop every now and then.

[Rseding91]

From what I can tell, and what others have tested for me, 100-120+ ms latency during upload is quite high - which I think is where your issue is coming from. Because it takes so long for a packet sent from you - the server - to get to anyone - the rate the game ends up sending packets is severely limited. It should be in the range of 20-60 for a "good" connection.

Sadly, I don't think there's anything you can do about it.

[TheFluteGnome]

Yeah, that makes sense. Thanks for looking into it so quickly. There might not be anything I can do about it on the Factorio side, but I've only just switched ISP's so I've time to contest it/drop out of the contract.

Happy to mark this one as complete but as a last part in case anyone else finds this whilst searching, this is what I used to test my connection stats: https://speed.cloudflare.com/

[TheFluteGnome]

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After talking to Vodafone about the issue (who made some changes on their end), and making sure I had all my network drivers etc updated, my upload latency has significantly improved. Unfortunately this doesn't seem to have fixed the map download problem. It's still downloading at about 400kBps.

Any ideas on what I could test next?

[Loewchen]

In the past there were problems with firewalls blocking udp packets because they assumed an attack when the map download started, but this was always a client not a server issue.

[TheFluteGnome]

Hmm, I can get them to double check. This is occuring across multiple clients though, who have had no changes to their firewalls since it stopped working. I'd have presumed it was something on my end not theirs as I'm the one that's had a big switch in conditions.

[Loewchen]

I'd take a step back and make sure that it actually is a networking issue. If you have a separate machine like a laptop create a .zip install of 1.1.87 on that, leave it default and only copy over the save file and sync mods with it. Now host the game but NOT in headless mode, if the issue persists it's a networking problem.

[TheFluteGnome]

Ok so, as you said I've tried it on a different machine with a new .zip of 1.1.87 with only the save and mods changed. Hosted as a "normal" in-game server, not headless client. Issue persisted. The map download speed seemed to hit exactly the same limit around 400 kBps.

Going to have a go with version 1.1.110 next, which I have been avoiding as I wasn't sure our mods would agree with it but no harm in trying.

[Atraps003]

A speed test to cloudflare doesn't mean much in this case. Vodafone's route to cloudflare can be fast while its route to your friend is slow. In the below speedtest example you can see that vodafone uploads much slower to att compared to another provider in the same city. In this example vodafone uses twelve99 to route to att and the other provider uses cogent.

Have they tried downloading during off peak hours? Do they have higher latency in game once they catch up? Do you mind opening up the server so others can check what speeds they get?

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[TheFluteGnome]

We've never actually had anyone connect that didn't already have the mods installed but presumably the sync function will take care of all that. If anyone wants to give it a go, I've made a backup so can leave it on. Address is:

factorio.arpc.co.uk

Time of day hasn't made any difference. After some more testing though, I'm pretty convinced it is something to do with Vodafone in particular. I've been in touch with their support multiple times over the last few days trying to get them to look into it with no real results. Having sat and watched the map download, it actually starts at 2MBps but then falls quickly to 400kBps, almost as if it's being throttled or capped somehow.

When connecting from another PC on my home network I get the following map download speeds:
Via local IP - 30MBps
Via public IP - 10MBps
Via public IP (but with VPN on to pretend to be an external PC) - 400kBps

[SoShootMe]

We've never actually had anyone connect that didn't already have the mods installed but presumably the sync function will take care of all that.

...All except LogisticTrainNetwork which shows as "No release".

Having sat and watched the map download, it actually starts at 2MBps but then falls quickly to 400kBps, almost as if it's being throttled or capped somehow.

That is a possibility, but it could also be due to the protocol Factorio uses, ie it is able to send data fast initially but then reduces speed based on (lack of) acknowledgement received by the server of what the client has received.

[TheFluteGnome]

In the end, after many unhelpful tech support calls, I bailed from Vodafone and swapped to Zen. Who knows what Vodafone were doing down the backend of their system, but on Zen my server is back to working absolutely fine.

If you have a similar problem and find this thread, then I'm sorry I never found a better answer!

Thanks all above for your time looking into it, appreciate that it in end this wasn't even really a factorio issue but you helped anyway so cheers.