steve wrote on 06/06/15 17:00:
Am nearing wits end... been away on hols for a month and my network
performance has plummeted.
The best way of describing the problem is that you need to refresh a
web page before you get any content. In addition, bulk loading across
a VPN ( eg scp ) fails regularly.
Basic design of network: 'firewall' server runs fail2ban and links
upstream ADSL to local wireless and wired subnets. It also provides
DNS ( caching server ), DHCP, OpenVPN etc services.
I initially thought it was a DNS problem, and have migrated from the
local ( Voda ) DNS servers to OpenDNS, having briefly tried Googles
resolvers on the way. No improvement.
Any thoughts on what I can try to identify the real problem? My
thought is that the GCSB are involved somewhere along the line, but as
a SysAdm I am paid to be paranoid!
OK - honestly I have no idea.... but I agree with Fraser in that "random
weird stuff" does often have root causes in DNS or MTU. But you've
appeared to rule them out.
So, cut the problem up.
1) Does the link test as slow when from the firewall box, as opposed to
a client machine?
If no then its a local network thing - isolate between wired
and wireless clients
If yes, then its an internet link.
2) How's the neighbour's speeds? Do they have Chorus ADSL?
3) Have you got any other ADSL routers to swap out? Its not unknown for
the hardware to just start dying from rubbish on the wire, specially if
its not completely urban.
4) Have you spoken with your ISP about getting line tests done? They can
do a 2 or 24 hour line test and monitor the stats from your DSL link,
which should give some indication of the DSL's performance. You can
continue to use it like normal for the test period too.
5) From memory you're in Diamond Harbour, so pretty SOOL for anything
like fibre. Would you have line of sight to Marleys hill? Probably
not. Would you entertain the thought of a wireless link across the
water? Do you know anyone in Lyttelton with fibre and LOS to your place ?
6) If you want to investigate further, do a tcpdump -i any -nn -w
poorlink.pcap -vv -s 1500
on your firewall, while testing from the internal host. Do something
to exhibit the problem, and then email me the pcap off list.
7) Finally, apply all windows updates, upgrade flash, java and acrobat
reader, do a antivirus scan and a malware scan, and restart your computer.
--
CF
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