I recently purchased the MAX Cat18 model and there are a couple major issues with it:
about 50% of the time when I turn the unit on, the internal AP does not broadcast at all (broadcast ssid is enabled). The only way to fix this is to reboot the unit, and then the internal AP will be running again.
the internal AP is extremely slow. I can get up to about 14-15mbps from it. If I plug in to the cat5 port I have no speed restriction, or if I connect a secondary wireless AP it works fine, but the internal AP is just ridiculously slow, especially given the cost of this unit.
QoS is disabled, no VPN, more or less stock configuration.
+1 I am having a similar issue. Have had mine for about 2 months now and no improvement with the issue. Rather irritating given the money spent on this and the antenna that I bought with it.
DTIM 15 did not help the situation on my end. I zeroed in on the issue (at least my version of it) being the fact that I both consume (wifi as wan) and provide (internal AP) signal at the same time and the CAT-18 having issues with it.
Disabling wifi as wan and focusing on cellular connectivity made the problem go away confirming at least in my case the issue.
Bought installed and wired an AP One and linked to the CAT-18 external AP management. Then turned off the CAT-18’s internal AP so it is dedicated to consumption of wifi as wan while the external AP provides signal to clients.
Only been a week but been trouble free whereas prior wifi would stop working several times a day.