We have 3 large sites, WLC5520 and 8510s all running 8.5.171.0
We have a Foreign/Anchor with external Company, the link for this comes to site 1.
Their WLC is a 5508 running 8.5.151
All 3 sites and WLCs anchor back to this 5508.
I'm getting intermittent control paths down only on 2 of the WLCs on site 1, but these are registered at different times.
Both WLCs are on the same Distribution blade, same config, on a 10Gb Connection, 1 is a 5520 and the other is a 8510.
If there was a issue with the the firewall to the 3rd party, I'd expect to see the Anchor fail on all WLCs at the same time, not just 2 at different times.
This install has been working for years.
cable from Switch to Firewall passes cable TDR test from switch, ports not being hammered.
We have several other Foreign/Anchor to other external company's and our DMZ WLCs, no issues