I'm in a similar dilemma finding a capable outdoor Wi-Fi AP and fearful of the potential waterproofing damage long-term from having the top cover off a Netmetal or a Basebox to mount antennas. It may be simpler to consider the wAP R ac based LTE/4G access points for your outdoor application (this is your other earlier post asking for recommendations for "a weatherproof outdoor unit solution"
viewtopic.php?f=3&t=162273 ). You mentioned in your subsequent response in that post that the Mikrotik sales team recommended a "wAP ac LTE kit should be able to cover 500m2 if placed in center".
The specs of the wAP R ac don't seem too different from the NetMetal ac²: IPQ-4018 128MB RAM POE out port for wAP R ac vs. IPQ-4019 256MB RAM and SFP port, as a well as a USB port if you need one. See the comparison – the wAP R ac seems to be really just a cAP ac in a wAP-type outdoor enclosure:
https://mikrotik.com/products/compare/R ... acD2HnD-NM
Moreover, you don't have to install a separate LTE/4G card and worry about getting the pigtails out to the top cover of the NetMetal ac². You'd have a lower Wi-Fi antenna gain with the wAP R ac, though—2dBi 2.4Ghz and 2.5dBi for the wAP R ac integrated antennas vs 3.3dBi 2.4 GHz and 5.5-7.1dBi 5 GHz for the HGO-antenna-OUT you'd use on the NetMetal ac². Taking into account the small loss on the internal pigtails, I'm not sure it would make much of a difference for 2.4Ghz. In any case, Given the nature of Wi-Fi coverage for smart phones, you may want to have a number of the wAP R ac APs spaced out in the area for your event rather than having just one or two NetMetal ac² with HGO-antenna-OUT antennas.
Would anyone be kind to share experience from having the wAP-type enclosure outdoors, say on a pole, for a long time – are there any serious waterproofing issues?