I'm using the ER605 V1 with newest firmware 1.1.1 Build 20210723 Rel.64608 in a private lan.
The WAN side is configured with IP 10.10.10.7 and the LAN side has 10.10.1.1.
Every 5 to 10 seconds there is a dns query to 10.10.10 and to . (single dot) coming from 10.10.10.7 (the WAN side of the ER605).
These queries don't appear when I disconnect the ER605 from the network (remove cable or power down).
On the LAN side no other devices are connected to the ER605.
I played around with the settings under Transmission - Load Balancing - Online Detection. None of the 3 possibilities stop these dns queries.

What is happening here and how to suppress these queries?

 
Sep 22 07:58:01 dnsmasq[13449]: query[type=311] 10.10.10 from 10.10.10.7
Sep 22 07:58:01 dnsmasq[13449]: forwarded 10.10.10 to 10.10.10.1
Sep 22 07:58:01 dnsmasq[13449]: reply error is 1
Sep 22 07:58:03 dnsmasq[13449]: query[A] . from 10.10.10.7
Sep 22 07:58:03 dnsmasq[13449]: cached . is NODATA-IPv4
Sep 22 07:58:03 dnsmasq[13449]: query[A] . from 10.10.10.7
Sep 22 07:58:03 dnsmasq[13449]: cached . is NODATA-IPv4
Sep 22 07:58:13 dnsmasq[13449]: query[A] . from 10.10.10.7
Sep 22 07:58:13 dnsmasq[13449]: cached . is NODATA-IPv4
Sep 22 07:58:13 dnsmasq[13449]: query[A] . from 10.10.10.7
Sep 22 07:58:13 dnsmasq[13449]: cached . is NODATA-IPv4