Major intermittent lag problems... Sometimes at peak hours, sometimes not. I've already checked that the problems happen even when nobody else in the house is using the link (ADSL, 4Mbps).

I've had my ISP (Plusnet) on the case, and they have attempted to add LFS to their traffic-management systems, using packet-captures I've supplied. However, they commented that it was the worst game they'd seen in terms of difficulty to recognise the game sessions.
Traffic management is used to make sure that packets for things like streaming video and online gaming get especially well treated, while lower priority things (e.g. ftp) can get held up.

Anyway, things clearly aren't working reliably yet, perhaps partly because LFS servers out there are using many different ports. It seems to be better on servers which use the standard port 63392... (Been studying rather a lot of pcap files :-/ ...)

Anyway, if people have advice, I'd appreciate it.
In particular, since traffic management by ISPs is probably fairly normal these days, how do other ISPs treat LFS? Should I change ISP?

Change ISP. I was with Plusnet for a few years and it was nothing but hassle with every sim i raced. They have the worst traffic shaping system I've ever come across.

After spending many more hours than a customer should have to, getting port info for all the sims i used in order for them to allow it on their system they would eventually (after several weeks usually) sort things out, only for things to go tits up again withing a few months. LFS was the worst case for the reasons you've stated, so many different ports being used.

I cant speak for other ISP's on their shaping, but since I've moved to Virgin I've had no problems with any game. As far as i know they don't shape traffic, they just throttle your bandwidth if you use more than the FUP allows depending on your package, which i have no problem with as i never get close to the limits.

(Basically on their 20Mb cable package there is no traffic shaping. You are limited to 7GB usage between 10am and 3pm and 3GB between 4pm and 9pm. Outside of those hours you can max you connection out 365 days a year and they wont bat an eyelid. If you can work within those limits then it's a perfect service in my experience. I've never seen anything less than 18Mb speeds at any times,never had no service and never had a dropped connection. They obviously have plenty of capacity, unlike Plusnet)

Plusnet had decent customer support guys and they were helpful enough, but the system they work with was more hassle than it's worth. I've now had a completely hassle free 14 months with Virgin and it's an absolute pleasure to use the internet again. It just works 24/7 whatever you are doing. I've had no cause to contact their support for anything since I've been with them. Plusnet were bad for my health. I spent more time in their support forums than gaming it felt like. They are (were? not checked their prices lately) also very expensive for what you get.

If you want hassle free gaming then I'd seriously look into another provider. Do your homework though. I'm sure there are many ISP's that are as much hassle as Plusnet out there.

Many thanks for the feedback Moose.

Will have to find another option than Virgin, though I do like their packages, cos we have no cable in our street. (Mucho frustrating, and the houses were only built 10-15 years ago, so it's bizarre.)
A whole family watching iPlayer, Youtube etc. etc. also pushes our usage up a bit, so I'll need a peak-time allowance of at least 20 or 30 GB I reckon

Such a shame about Plusnet... they used to be so great. But I agree that the traffic management does seem over-zealous.
I had assumed that more or less every ISP was doing it now but having done a wee bit of research now (and judging from your experience) I seem to be quite wrong about that...

(PS: I think you should count yourself very lucky you've not needed to talk to the Virgin support guys - that is, if I'm remembering correctly that it's the ex-NTL crew. NTL were spectacularly awful in most cases - I have some friends who had issues with NTL and the tech support was sometimes so bad it was hard to believe it wasn't malicious But when it's working, it's a great service and also great value.)

OK, getting ready to pull the plug on Plusnet, since the problems haven't gone away (except intermittently) and no feedback about it for over a month now.

Am considering Xilo.net, who seem currently to be rebranding their broadband offering as "Uno broadband".

They seem to be a small outfit, and among other things they resell C&W LLU ADSL2+ which is what I'd be going for. (It's "partial" LLU, inasmuch as the phoneline stays with BT.)

The package I'd go for is £15 ex VAT per month, "unmetered" (they confirmed that a good fraction of 100GB per month is no big deal), and has no traffic shaping...

Anybody have any experience with them for LFS?