It would be helpful to know the ISP modem model if you can give feed back when you get home.
This could be an issue. Depending on model and signal quality of the ISP service and this model.
I recommend that you have your ISP check the cabling going to the ISP modem, check signal levels going to the ISP modem. For DSL or Fiber service lines, ensure that the ISP is using good working phone or cable lines to the DSL modem and that the phone lines are filtered correctly. For cable Internet,
RG-6 coaxial cable is needed, not
RG-59. Check for t.v. line splitters and remove them as they can introduce noise on the line and lower the signal going to the ISP modem. I recommend having the ISP service physically check the lines going from the out side to the ISP modem. Connecting to the ISP modem could result in a false positive as the signal to the modem could be just enough to that point then adding on a router, could see problems.
The router operation is dependent upon getting good data flow from the ISP modem and the modem is dependent upon getting good signal from the ISP Service.I use a Motorola SB 6121 with my DIR-655 Rev B using v2.11 Mod FW and it's been handling the entire house hold just fine.
http://forums.dlink.com/index.php?topic=55233.msg271069#msg271069Sometimes routers may need a clean fresh reload of FW and set up from scratch as well. I would give this a try:
Link>
>FW Update ProcessOne way to help figure if the router or and ISP issue. Turn OFF the WiFi radio on the 655 and see the problem continues.
Try direct connect with a PC to the ISP modem to see if the problem continues or not.
If the 655 seems to be ok on the wired side and maybe wireless is not as good however you still want the wired side of the 655 and keeping the UI features, you can always disable the wifi radio on the 655 and connect up a wireless AP connected via LAN cable to the back of the 655 as a alternative wireless upgrade. I've ran a couple of different AC class wireless devices with the 655 for testing. I have a DIR-868L, DIR-857 and a DIR-615 connected as APs currently. All works great.