Suggest your guys submit a ticket to report such a problem like ragnarokgr did.
http://ticket.tp-link.com/index.php?/Tickets/Submit

UPDATE: Got my speed issues figured out (something in startup eating all my bandwidth) but the dropped connection issues persist. It will be fine for a day or so, then drop several times in an hour. So weird--especially since the connection was rock solid until a Centurylink tech switched my line from G.dmt to ADSL2+. Now it's spotty at best. I set my DSL Modulation Type to G.dmt thinking that would straighten it out, but it hasn't. Any other tweaks I can make to my router/modem? Or do I need to call CL and get the line downgraded? My max speeds are about 6 MB down.

I opened a ticket in the tp-link and i explained the whole problem but they do not care much to resolve, and it seems, will not come any firmware update for this.
I performed some tests here.
Some observations:
* I've tried other modems (other brands) and the connection did not fall. That is, the problem is certainly the TP-W8980.
* I configured a bandwidth limit in W8980, my hired band is 11296 kbps, i set it for the 10000kbps and make new testings, the conection not drops more while make downloads with maximum band. I reported this to the tp-link(ticket) and he suggested me taking this action (shameful suggestion).

jbird5150 wrote

UPDATE: Got my speed issues figured out (something in startup eating all my bandwidth) but the dropped connection issues persist. It will be fine for a day or so, then drop several times in an hour. So weird--especially since the connection was rock solid until a Centurylink tech switched my line from G.dmt to ADSL2+. Now it's spotty at best. I set my DSL Modulation Type to G.dmt thinking that would straighten it out, but it hasn't. Any other tweaks I can make to my router/modem? Or do I need to call CL and get the line downgraded? My max speeds are about 6 MB down.

Friend, your problem seems to be different from ours. In our case, the ISP service is good, well-qualified, but when we try make a download at maximum speed using the TD-W8980 modem then the connection drops. On you case, you seem to be having trouble getting good speed between the modem and the computer.

Frequent disconnections occur when you exceed the suppliers speed. The servers on suppliers side limit temporarily. this is because the router is more efficient than one that seems to work Ok. Try limiting the speed of downloading and increasing till you reach a point where it does not disconnect.

ragnarokgr wrote

Region : Greece

Model : TD-W8980

Hardware Version : V1

Firmware Version : 0.6.0 1.8 v000e.0 Build 150514 Rel.40138n

ISP : Forthnet

As the title says whenever i am downloading something with close to max speed the internet always drops for few seconds and comes back online.
Logs suggest authentication error of some kind though i can't understand why.

26	2015-06-11 13:36:57	PPP	Error	ppp0 User request
27	2015-06-11 13:36:54	PPP	Information	ppp0 sent [LCP TermAck id=0x2]
28	2015-06-11 13:36:54	PPP	Warning	ppp0 LCP down
29	2015-06-11 13:36:54	PPP	Error	ppp0 LCP down
30	2015-06-11 13:36:54	PPP	Information	ppp0 rcvd [LCP TermReq id=0x2]

Have tested with another router and there is no such problem. Is is hardware problem? is it settings?

vpi is 8, vci is 35 as per specification. PPPoE with 1492 MTU and authentication is auto though its pap anyway.

Problem is reproducible everytime though if i don't download at max speeds everything is fine.

BREN wrote

Frequent disconnections occur when you exceed the suppliers speed. The servers on suppliers side limit temporarily. this is because the router is more efficient than one that seems to work Ok. Try limiting the speed of downloading and increasing till you reach a point where it does not disconnect.

I am sorry but bandwidth control isn't really the solution. I already have a cheap router that works at the same speeds only slightly less like 2.13mb/s instead of 2.19mb/s and the difference is clear as day and night. The tp-link router i have must be defective cause i get serious buffer bloat compared to the cheap router i use now. I took the tp-link router to the supplier which they told me works fine but again the problem is there so i took it back to them hoping that they figure what is wrong because their solution was just to update the firmware which i already had the latest one. I won't settle with using bandwidth control to fix something that is caused by a faulty router, unless of course the router is fine but that would mean that the tp-link routers are just bad which i hope isn't the case.

BREN wrote

Frequent disconnections occur when you exceed the suppliers speed. The servers on suppliers side limit temporarily. this is because the router is more efficient than one that seems to work Ok. Try limiting the speed of downloading and increasing till you reach a point where it does not disconnect.

I tested Dlink model 2740e(low cost model) and i make downloads with maximum bandwidth without problems, my bandwidth contracted is 11296Kbps, then i make downloads with 1.40 MB/s with the d-link but not with the tp-link, because tp-link w-8980 drops the connection.
I limited the bandwidth for 10000Kbps in tp-link and the connection stopped falling, but I lost exact 1296Kbps, is a big difference in speed. So your hypothesis is wrong, because with the dlink i can make downloads more faster than of the tp-link w8980, and logical, without falls.

Hi
I' m facing something similar except I'm not able to connect the device when it falls (192.168.1.1 not responding, PC says limited conexion) and I need to turn off and on (ocurred 2 times today). In ly case it's not easy to reproduce the freeze.
What told BREN makes sense I think: Sometimes my download speed exceeds the expected speed (5Mbits contract but downloading @640KB). Even considering that fact there is a problem with the modem part of this router because using an other one the problem does not occurs.
I'm now testing using BandWidth control and will report back soon. If problem persists I will configure the 8980 as a router only without modem, why not but I'm a little bit disapointed with this product. I also noticed that the device is quiet hot with 28°C in the room. And here it's winter... so I mounted a fan below it to avoid a fire when summer will come back....

He really works hot here too. But analyze with me, sometimes my download also exceeds the contracted bandwidth, with the TD-w8980 and others modems, but the only the occurs the drop is the tp-link. This is not a sign of better efficiency but less efficient in relation a others modens.
I opened a ticket in the tp-link support days ago and so far nothing has been resolved and probably will not solve.
I've tried everything and the only way was limit the download bandwidth well below the contracted. I think the only solution would be a firmware update, which probably will not come from tp-link.

you're right, anyway it's a bug from tp-link firmware and considering the device age they will probably not make an update and sell the last units. :(
Currently I put the bandwidth to 5200 for a 5Mbits contract with tp-link status showing a Current Rate of 5660. By the way I don't know why these 5660 as my ISP is not the kind that will give 11% more bandwidth...
For now, it's ok and I will give a feedback if something changes.
thanks