Wireless Access

We've been noticing intermittently that a handful of PCs connected through RAPs for work at home will stop communicating to the network & subsequently lose network access all together. During this time, I've verified the RAP remains reachable from the MD by pinging the Inner-IP address, and also have checked the remote ARP table on the RAP to see the PC's MAC/IP is still present. This usually clears up anywhere from 20 seconds to 2 minutes later on it's own. We've not been able to identify a root cause with this being a remote setup. I'm wondering if anyone else has come across this, or has any suggestions for troubleshooting? 

Thanks!

I've taken a few steps to try and identify if the PC just refuses to respond or if the VPN is not passing the traffic. I've enabled SSH (we're on 8.7.1.9) to the RAP and verified I can remotely access it through the MD. On the MD, i can then run a "show ap monitor arp-cache ap-name <ap-name>" to get the ARP table on the RAP and I can issue a ping to the PC's IP address. Given the ARP cache on the RAP, I'm hoping the ping will be directly to the PC and not go through the VPN tunnel. I'm hoping this will at least narrow down the location of the problem for further review. If I'm able to gain more insight into this problem, I will share.