az login returns error "Failed to establish a new connection: [Errno -3] Temporary failure in name resolution" - networking

Question

I was doing az login from WSL of my windows machine. Then it gives an error:
Please ensure you have network connection. Error detail: HTTPSConnectionPool(host='login.microsoftonline.com', port=443): Max retries exceeded with url: /common/oauth2/token (Caused by NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7f401d135630>: Failed to establish a new connection: [Errno -3] Temporary failure in name resolution',))
I hope this is a DNS issue.
So I checked /etc/resolv.conf of WSL:
# This file was automatically generated by WSL. To stop automatic generation of this file, remove this line.
nameserver 192.168.1.1
nameserver fcc0:0:0:ffff::1
nameserver fcc0:0:0:ffff::2
192.168.1.1 is the default gateway.
There are the results of some commands I tried:
$ ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
64 bytes from 192.168.1.1: icmp_seq=1 ttl=128 time=0.351 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=128 time=0.888 ms
64 bytes from 192.168.1.1: icmp_seq=3 ttl=128 time=0.883 ms
$ dig 192.168.1.1
; <<>> DiG 9.11.3-1ubuntu1.3-Ubuntu <<>> 192.168.1.1
;; global options: +cmd
;; connection timed out; no servers could be reached
$ nslookup 192.168.1.1
;; connection timed out; no servers could be reached
These commands also give an output that indicates an issue.
Ping google.com
dig google.com
All these commands( or its alternatives) work from the Windows command prompt works correctly.
I found a workaround here:
https://askubuntu.com/questions/91543/apt-get-update-fails-to-fetch-files-temporary-failure-resolving-error
It says that I should add the followinng line to /etc/resolv.conf. If I try it like this, it works.
nameserver 192.168.1.1
nameserver 8.8.8.8
nameserver fcc0:0:0:ffff::1
nameserver fcc0:0:0:ffff::2
After this, the ping google.com and dig google.com works fine. But I can see that the nameserver it uses to resolve is 8.8.8.8.
If I connect to VPN, it adds our own nameservers to /etc/resolv.conf and after that, there is no problem in resolving the URLs. Once the VPN is disconnected, the issue arises again.
Note:
There were no issues like this before.
Last day we changed our router in order to use a new ISP's connection and after that, the issue occurs.
Other machines in the same network don't have this issue.
Why this occurs and How can I properly fix this issue of WSL?
Why only one machine in our network can ping, but can't dig to the default gateway?
Update:
I can see that there are two entries that are marked as default in routing table:
$ ip route show table all | grep default
none default via 192.168.0.1 dev wifi0 proto unspec metric 0
none default via 192.168.1.1 dev eth6 proto unspec metric 0