Thank you for the feedback. You are probably right; this is indeed acting as layer 2 access switch and some of the configuration may be outdated.  ... View more

Got it . We have a Fortigate firewall indeed , will see how I can apply Qos to it .  Thank you both  ... View more

The newer firmware versions do pick up more errors than the older ones, ports running at 100Mb instead of 1Gb for example.  So it may be that you had at least some of the problems before, but they weren't being so actively reported.  If you are seeing cable test failures from the switch tester, try a physical cable tester to confirm the fault is genuine, it usually is, but just to be sure.  ... View more

@alemabrahao    Its now sorted ,  it looked like some of the  " Firewall & traffic shaping " rules for the relevant site were preventing clients traffic to get to the DNS Server .   Thanks All for your help    ... View more

So you had tagged the VLAN on the AP, now it makes sense, if it had not been tagged the AP would receive the IP of the native VLAN (not tagged), maybe you missed informing this detail. ... View more

Hi All   Just to let you know  the matter is now solved . Our on Prem Firewall had a Zone protection profile  with a setting instructing  the firewall to drop fragmented traffic . Once  that setting was updated it worked .   Thanks all for your contributions ... View more