Just want to share my findings on the best ADSL modems to maintain stability of the internet connection. In a nutshell, the chipset used for ADSL connections is an important criteria and the cable distance from nearest DSLAM exchange to the modem should determine what chipset/modem to use.

If your downlink Snr is low (<15), try broadcom/lantiq based modems.
If dslam exchange is near to your house (<2.5km cable length), trendchip based modems work best.
Lantiq based modems seem to work well on both long/short distance, sync quite high, but there are not many models to choose from, user reports aren't many but most people give good ratings.
If your downlink Snr is very low (<10), or you need to reset router frequently, definitely use broadcom.

Changing modems will not totally solve adsl connection problems, each scenario is unique and should be tackled from all angles (wiring, noise on line, network configuration, type of usage etc)

Many older modems from d-link are based on broadcom chipset, including some supplied by TM Streamyx, gives better stability based on my own experience.

Avoid stressing the modem with routing and wireless functions, even though the unit is sold as a wireless router. Configure modem as bridging modem, then install separate unit(s) for routing and|or wireless. Use the modem only to connect to ISP and do nothing else but maintain good sync.

If you use the modem as a router and/or wireless, under heavy load will over-heat or simply lock-up (hang!), especially if you do P2P or torrenting heavily.

P2P/torrents will require a modem with larger NAT table (higher RAM) due to simultaneous max connections.

My list below does not include high-end/expensive modem routers.

Common chipset manufacturer for adsl modems:

trendchip, works best < 2.5km cable length from exchange
buffalo wbmr-g54?
asusdlink dsl-n12u, combo ralink + trendchip
asusdlink dsl-n55u
buffalo wmbr-hp-gnv2, ralink + trendchip
tp-link td-w8968

broadcom, > 2.5km from exchange, better stability on internet connection, some models can tweak SNr via telnet of webgui
bcm6328
dlink dsl-2640u/nru/c4
dlink dsl-2640u/nru/cb4a
dlink dsl-2650u/nru/c
dlink dsl-2740u/nru/c5
dlink dsl-2750u/nru/c5 rj-11 cybermind $69
bcm6332
dlink dsl-2500u/bru/c/d/db
dlink dsl-2520u/bru/c/d
dlink dsl-2540u/bru/d
dlink dsl-520b-se
bcm6338
asus am604
asus wl-am602
asus wl-am604
dlink dsl-2300u
dlink dsl-2320b
dlink dsl-2500u
dlink dsl-2520u
dlink dsl-2540u/bru/c/cb
dlink dsl-2600u/bru/c
dlink dsl-2640u/bru/c/c2/cb
bcm6345
asus aam6010ev-m
asus aam6030vi-b1
bcm6348
asus am604g
dlink dsl-2640u/b/bru/d, I got 2640b from TM!
dlink dsl-2641b
dlink dsl-2642b
asus dsl-g31
linksys wag54gs
linksys wag54gx2
asus wl-600g
asus wl-am604g
bcm6358, same chipset as billion 7800n
buffalo wbmr-g300n
dlink dsl-2650b/bu/u/bru/d
dlink dsl-2740b/u/bru/c2
dlink dsl-2741b, ver. c2
dlink dsl-2760u/bru/d1/d2
dva-g3672b
huawei hg553
td-w8960n v1.0-1.6 bcm6358 bcm6301 32/4mb, same chip as billion 7800n
td-w8960n v1-v3 bcm6358, same chip as billion 7800n
thomson tg782t 64mb ram $20 ebay
netcomm nbw9maxx
2wire 2071a non-wireless
bcm6368
dlink dsl-6540u
dlink dsl-6740u
unknown broadcom chipset
netgear dgn2200 n300 adsl2+ ethernet 32/8mb $99, hw v1 support openwrt
archer d7
huawei hg644b 64/8mb, tm unifi router, no openwrt support, no vendor firmware
cisco/linksys x1000, lemon poor modem
cisco/linksys x3000
cisco/linksys x3500
netgear dgnd3700

lantiq, work well on both long/short distance, sync quite high, SNr cannot tweak
smc7908wbra ?
wbmr-hp-g300h adsl2+ gigabit 11bgn ram 64mb, flash 32mb, support openwrt fully but vlan bug?
tp-link td-w8970, td-8970b ram 64mb, flash 8mb, openwrt works but no wifi
tp-link td-w8980, td-w8980b, to gain vdsl feature, use td-w9980 firmware
tp-link td-w9980, td-w9980b, same hardware specs as td-w8980

ralink
tplink n150 adsl td-w8951nd, similar hw as tm modem riger db-120wl
tp-link td-w8961nd
asus dsl-n12u, combo ralink + trendchip
buffalo wmbr-hp-gnv2, ralink + trendchip

Related links
http://www.modem-help.co.uk/Broadcom/chipset.types/ (look for section xDSL CPE)
http://wiki.openwrt.org/toh/start (show RAM info for some models)
https://wikidevi.com/wiki/Broadcom#xDSL

This post has been edited by pokipoki08: Nov 1 2014, 10:41 PM

hi,
good info

BTw, I am choosing a TPlink modem i.e. TD-W68968, TD-W8970, but not sure abt my cable length to exchange. What do u recommend. tq