Over the years I have used a variety of makes of ADSL routers both bought by myself and some provided by ISPs. I currently use an O2 provided Wireless Box II with Sky since they bought O2 Broadband. (I am still with Sky.)

I have just bought a new Draytek Vigor 2860 since I wanted a router with SNMP support and all the other features it has of ADSL and VDSL support, better DDNS support, Gigabit Ethernet, built-in VPN server, MER support, IPv6, etc. were all things I also wanted although I might not use them all immediately. I am fed up with crippled routers from ISPs.

I got the Vigor working with O2/Sky straight away with no problems but now have some questions. For your information I am running 3.7.4.1 firmware.

1. With ADSL and Sky, which of the two ADSL modem codes in the Vigor2860 is best to use?
2. As mentioned it is successfully connecting to Sky - so I am presumably using correct settings I used the following as a guide

http://helpforum.sky.com/t5/Broadband-Setup-Connection-WiFi/Moving-from-O2-to-Sky-Broadband-using-a-router-that-wasn-t/ta-p/1470481

however, I was wondering if other people may have suggestions for additional/different settings which might improve speeds even a little bit. I am currently getting a SpeedTest.net result of about 12Mbps on the Vigor but was getting about 15Mbps on the O2 Wireless Box II.
3. I am noticing that after booting the Vigor2860 it takes much longer to apparently start the PPPoA connection compared to the O2 box. This is not the time the Vigor takes to boot which is very quick, but after it has booted it seems to take quite a while before it tries connecting over ADSL. Again are there any settings which might help improve this. I do have it currently set to use auto detect for ADSL/VDSL rather than forcing just ADSL but it seems to detect it is ADSL quite quickly but still waits a fair time before starting the PPPoA connection.
4. Is there any speed benefit either in terms of throughput or in terms of how fast it negotiates the connection from using MER instead of PPPoA? My current O2 box only does PPPoA but as mentioned above the Vigor also supports Sky's MER mode.

To decrease sync. time, you can set it to the specific DSL type, e.g. G.DMT, VDSL or whatever rather than 'auto'.

the modem codes sometimes can make difference but you need to test for your line which one is more better. even if not give you better speed, watch the errors (physical connection>on line status>ATM statistics) & see which one is more stable, in the future should add some more codes
To start faster the connection set manually with adsl & also set the modulation to adsl2+(g 9992,5), this will avoid the modem to search for what modulation the line is using and will lock with the one was set, so in theory it should be faster synchronize
Also set the correct MTU size from your isp

I don't have the 2860 yet but give a go at the telnet - if works (top right the gray button looking like equalizer)with the command
adsl snr -20
and let me know if will work