Tplink TD-W9980 & 5Ghz wifi

[#1]

Recently I have been using some stuff connected to the 5Ghz wifi, Internet etc works find but when it is on 5Ghz I can't connect/ping it from the local network.

There is NO firewall rule to disable access to the local network, and if I switch the unit to 2.4 it connects fine.

Anybody come across this before?

[#2]

I have the same router, 5Ghz seems fine.  Have you applied an Open-WRT hack, reason I ask is that the 5Ghz doesn't work on WRT.

[#3]

No I haven't. Strangely it has started working.
Only change was the phone was re-booted. And no it isn't a M$ phone 😉