Hotspot QOS/throttling

Question

I have created a guest hotspot (separate zone), and noticed that the speed is being throttled somehow (around 3mbps on a 160mbps connection). I cant seem to find out why, there are no qos settings enabled as far as I can see. 
 on another wireless network bridged to lan through the same AP, the speed is as expected.

JonMeacham · Answer

Hi Bob, a bit of searching reveals the issue is MTU on the private zone network. 
 
 https://community.sophos.com/products/unified-threat-management/f/wireless-security/56513/bad-throughput-after-9-30#pi2353=8 
 
 MTU at 1280 solves it, but may cause other issues? 
 
 Thought this would have been solved by now 
 
 9.603-1 / AP15C 
 Have logged a support case. 
 Jon