Sorry if i've not read every single post, quite a long thread, maybe it was already mentioned..
re: stalling web pages, that seem to work over VPN or messages like "Establishing secure connection" in chrome ... have you tried setting the MTU to 1400 ? I believe even the routers supplied by three have them set to 1440 but setting it to 1400 resolved all of that issue on my friends 535.
He was getting good speeds, over 70mbit, but pages would take ages to establish the connection. Works perfectly now.
This only applies to the three network though, an EE sim in the same router worked fine with the default MTU. But I think they've also got some weird transparent proxying going on as well.
Hey dabigm,
thanks for the hint, but Linux should normally do proper path mtu testing by default.
I've checked it, to be sure, and indeed my internet provider supplies me with a proper path mtu of 1500. So there's no issue here.
I can also reliably trigger this, by opening more connections - so when I close some programs which establish connections the issue will disappear.
Huawei Customer service btw replied to my request, and stated, and I quote:
"Maybe your internet connection is not that strong, because if your
device meets all 4 bars and the connection is still slow, it is not the
not the device itself.
Please note that when you download something, the connection is slowed down."
So there definitely onto something :'D
Anyway - I wrote them an answer. I actually had a smaller Huawei router in the same position before, and it hasn't had any issues. So there's definitely some "web filtering" stuff still on this model, even when the firewall is deactivated - which causes this issue.
I'll gonna have a look at the firmware and report back if I find the time to work out a solution.
This only applies to the three network though, an EE sim in the same router worked fine with the default MTU. But I think they've also got some weird transparent proxying going on as well.
Nope, no proxying, but tunneling. I think you found that they use IPv4 over IPv6 tunneling and don't properly handle too large packages. Normally IPv4 expects that packages are fragmented by routers which can't handle the full 1500 byte size. If not, there's an ICMP to inform the sending computer, that the package is too large, if the "do not fragment" flag is set. The network stack then sends smaller packages.
But IPv6 doesn't bother with this bs. The packages are always "do not fragment" and routers will never fragment packages, but instead send an ICMP.
But somewhere in most ISPs setups they tend to brake something and the "package too big" info from the IPv6 side isn't reaching the sending IPv4 host.
That's called an PMTUD blackhole.