Speed problems

[#1]

Hi, Is there a problem in the network or at our exchange I wonder?
Normal speeds of 1Mbps up and 10+Mbps down have gone totally with <2Mps down, .5 to .9 up.
Router and cabling checked here - no changes either.
Router PPoA dropped/restarted to gateway hop - no difference
Router rebooted - no difference.
Router Stats (Draytek 2850vn) showing good sync rate and SNR - 16Mbps dl, 1 Mbps ul, and 3 SNR. Line attenuation normal for this line at 26.
ATM Statistics TX Cells RX Cells              TX CRC errs RX CRC errs
                          220260 1641989                0                    38747
All PCs on LAN sufering equally so not a local system problem. LAN performance is fine, only the WAN is suffering.
Help!?! 

[#2]

Hi there,
There's nothing reported. 
Can your run a speed test at http://speedtest.btwholesale.com and run further diagnostic after the test has completed.
Check which gateway you're on at http://usertools.plus.net/@gateway/
Run a pingpath command, to run the pingpath command you'd need to open a command prompt and type the following, 'pathping ntp.plus.net -q 50'

[#3]

Hi there,
It looks like it may be due to <a href="http://community.plus.net/forum/index.php/topic,111170.0.html">this</a>.
If it happens again can you run through a few checks so we can see what is going on?
Can your run a speed test at http://speedtest.btwholesale.com and run further diagnostic after the test has completed.
Check which gateway you're on at http://usertools.plus.net/@gateway/
Run a pingpath command, to run the pingpath command you'd need to open a command prompt and type the following, 'pathping ntp.plus.net -q 50'
Chris