This is a malware domain, blocked by Mastercard.
Use dig command to see which dns providers actually block this malicious domain. (OpenDNS free plan does not block it, while Cisco Umbrella paid tier, blocks it as malware)
For example
dig a4p.adpartner.pro @9.9.9.9
We are out of topic, but since we are talking about dns, I would post my thoughts:
Cisco Umbrella/Opendns:
+Spend the most money on dns infrastructure than anyone else
+Don't add any experimental features
-Have no malware blocking on the free tier.
Google DNS:
+Many locations and good...
You can set Domain Overrides on Unbound, so you will use other dns servers for these domains that get blocked.
I'm saying this because you may face blocks using other dns services too.
Some channels can transmit at higher power than others, due to local regulations. For example if you compare a channel higher than 100 with channel 36, the later range will be reduced significantly. When comparing 2 APs, use the exact same channel.