New router - slow speeds

[#1]

A couple of weeks ago a passing thunderstorm took a dislike to my Plusnet supplied Technicolor modem/router and trashed it. As the wireless strength of thie router had always been poor I decided rather than replace like with like I'd purchase my own router with decent wireless range, so I purchased a TP-Link W8970.
The wireless is now great however my download speed is only half of what I was getting with the old router and indeed the BT Voyager router I was using before that. I'm on ADSL2 and when my max speed was only ever about 1.6Mbps the reduction to 0.8Mbps is a proper slap in the face.
Here are the line stats from the new router
                                          U      D
Current Rate (Kbps) 728 1056
Max Rate (Kbps)         728 1536
SNR Margin (dB)             6   7.2
Line Attenuation (dB) 39.1  63.5
Errors (Pkts)                     0   0
Unfortunately I don't have them from my old router but it's quite obvious that my line is syncing at a much lower rate than previously.
It's only been a couple of days since I started using the new router and I'm not sure if over time these stats will improve.
I've done some research online and have seen some suggestions that perhaps this new router is not ideal for medium to long lines.
Does anyone have any suggestions or observations.
Thanks,
Kevin

[#2]

As it has a different chipset (Lantiq as opposed to Broadcom) that may be a factor
When did the router last resync
I ask because either it was over night at 6dB default and, in this case a resynch around midday may improve things
or it was during the day with a default noise margin of 9dB which has dropped due to losing the higher frequency bins
Either way a resynch (click on disconnect first to stop the PPP connection then connect if needed after a resync) with the stats immediately after would tell us a lot

[#3]

Just resynched and these are the stats
Current Rate (Kbps) 832 1660
Max Rate (Kbps) 836 1660
SNR Margin (dB) 6 3.2
Line Attenuation (dB) 39 64.8
Errors (Pkts) 0 0
Seems to have synced at a much higher rate which I hope is promising.

[#4]

In which case I suspect that you had a problem over night when the line became unstable and it resynched at a much lower speed
You will need to monitor it to see what happens to the noise margin after dark and whether it can hold sync over night

[#5]

Thanks for the help. I'll keep an eye on it.