Intermittent throughput drops on AC bridge

[sirdione]

Main router: R8000
Wireless Bridge: R7000
Computer A: Windows 8.1 64-bit, hard-wired to R8000.
Computer B: Windows 8 64-bit, hard-wired to R7000.

When transferring files from computer A to a network share on computer B, I initially see speeds averaging around 70 MB/sec (spikes over 90, sometimes dips into the 50's) and usually fairly steady. I get 1 ms pings between machines and no packet loss. It's a rock solid connection!

The problem is that after some time (sometimes ten minutes, sometimes a few hours), transfer speeds drop significantly to less than 24 MB/sec, sometimes in both directions, but usually in only one direction (random). Transfers are VERY STEADY and it looks as if it's being throttled by something. Pings still show good responsiveness and no packet loss. Sometimes it's 24 MB/sec, sometimes 23 MB/sec, sometimes 21 MB/sec. In either case, it's VERY STEADY, as if being throttled.

Rebooting the main router temporarily fixes the problem.
Rebooting the bridge temporarily fixes the problem.
Rebooting PC A temporarily fixes the problem.
Rebooting PC B temporarily fixes the problem.
Changing any settings for the network adapter in computer A temporarily fixes the problem.
Changing any settings for the network adapter in computer B temporarily fixes the problem.

I normally copy files to a UNC path on computer B that starts with the computer name. While experiencing the slowness problem, if I instead use the internal IP address for computer B in the UNC path, the fast speeds return! However, if I continue using the IP address in the path, eventually the problem returns. BUT, when I switch back to using the computer name in the path, the fast speeds again return! This behavior is what really has me stumped and thinking that it's an issue with Windows 8/8.1 and not the router or bridge.

W. T. F. ?????

Note that the problem occurs even when the bridge is in the same room as the router. There are no other radios operating on the 5 GHz band. I have tried multiple channels. I have tried not allowing any other wireless clients to connect to the same radio. I have tried using a PCI-E Intel netowrk adapter in both computer A and computer B (thinking the problem was with one of the network controllers). I have tried disabling many settings on the network adapters (green settings, checksum offloading, etc.). Computer B used to have Windows 8.1 64-bit installed, and I wiped it and loaded 8, hoping to resolve this issue.

I have experienced this problem with several combinations of five different routers, so I am not sure that it is related to the actual wireless equipment or settings. However, it only happens over a wireless bridge. Even when file transfers are slow, it's still a reliable connection. Computer B is running Plex, and I can easily stream video to multiple devices (Roku 3,iPad, etc.) simultaneously. It's just driving me crazy that my file transfers slow down.

Unfortunately, I don't have any other PC's that I can use to test this any further. If the problem is due to just one of my PC's, I don't know which is the cause. However, the problem occurs even when computer A is wired to the bridge and computer B is wired to the router. When both PC's are wired to the same switch (R8000, R7000, or separate switch), I get steady Gbit transfers. It's only when the bridge is between them that the problem occurs.

Does anyone have any ideas? This is very frustrating. I am almost ready to give up and accept the N-like speeds even though it should be a fast AC connection. Running ethernet is NOT an option. Any help is greatly appreciated.

I wiped computer B (connected to the bridge) and installed Windows 7. The issue did not go away.

I wiped computer A (hard-wired to router) and installed Windows 7. The problem is gone! I've gone two days without issue running Windows 7 on both machines. That is, by far, the longest I've managed to go without the speed dropping. In most cases, I couldn't go more than an hour. My transfer speeds for large files rarely drop below 60 MB/sec, and sometimes reach more than 90.

I spent countless hours over a period of several weeks trying to get this thing working. This is just one more reason for me to hate Windows 8. I can't believe how much time I wasted.

Sorry to necro an old thread but this is the closest thing I've found to my own problem after scouring the internet.

This seems very similar to my situation. Computer A (desktop) hardwired to Asus RT-AC68U router. Computer B (laptop) hardwired to D-link DIR-868L configured in bridge mode. Both computers have SSDs and both are Windows 7 64bit, but the desktop is Win 7 Pro. The wireless bridge is one floor up but in the room right above the router and the signal is very stable and very strong. I've monitored the signal strength during transfers and there isn't any random dips in connection or interfering 5 GHz signals. So, I have a full strength 802.11ac connection on 5 GHz operating on three spatial streams. I should get a theoretical max transfer rate of about 80MB/s. And that's exactly what I see when moving a 2GB mkv from A to B, and testing with a stopwatch--when both computers have been freshly rebooted. It can stay fast like that for a while. However, randomly I'll see the transfer rate drop to around 24MB/s, and once it has dropped it'll just stay there like it's throttled for some reason. The various reboot steps that the OP mentions also works for me to restore the fast/full transfer rate.

Unfortunately, the solution for the OP doesn't seem to apply to me, since I was never running Windows 8. Is there a chance that Windows 7 Pro has a similar issue to Win 8?

Any other thoughts or ideas on how to fix the random drops in transfer rate?

Thanks!