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.
You might try a FW reload, factory reset, load v2.11, then factory reset.
Also you might try the ISP modem is router mode then place the 655 into the DMZ on the modem and test...
Is Qos Enabled, It should be disabled.
- Turn off Advanced DNS Services if you have this option under Setup/Internet/Manual or under Setup/PARENTAL CONTROL/Set to>None: Static IP or Obtain Automatically From ISP.
- Enable or Disable Use Unicasting (compatibility for some ISP DHCP Servers) and test under Setup/Internet/Manual. Disable may help with speed performance on higher speed ISP services.
- Turn OFF DNS Relay under Setup/Networking. Link>Finding Faster DNS Addresses using Name Bench and input new DNS addresses under Setup/Internet/Manual.