Request-to-send flood on Wireless Network

Question

I'm experiencing constant intermittent lag spikes from my wireless network and decided the investigate using wireshark.

I found out that during one of the spikes, the transmitting address (Station A), which happens to be my wireless router (Engenius ESR9850), is sending out 25 of these RTS packets.

540 0.201225 Station A (TA) Station B (RA) 802.11 52 Request-to-send, Flags=........C

I've exhausted all my options trying to eliminate the lag spike. These are the following things I've tried.

1. Changing the wireless channel (It is using channel 11 now)
2. Changing the preamble (Short)
3. Changing the transmission bandwidth (20mhz)
4. Changing the RTS and fragmentation threshold (2306/2307)

Here are some additional info:

• Wireless mode: b/g/n
• Encryption: WPA2-PSK

Is the router going rogue?? It is also linked to an ESR6670 via WDS. Station B is probably connected to the ESR6670 when this happened.

Any ideas? :/