quad9 + DoH issues?

RouterOS General
1

I have had several interruptions to quad9 + DoH over the last 24 hours. It is normally reliable.
My configuration uses 9.9.9.9 and 149.112.112.112.
Symptoms are multiple messages with errors 403 or 502.
This was seen under RouterOS 7.17.2 (I have now updated to 7.18).
I’m in Cambridge, UK and my ISP is Virgin Media.
Anybody else seeing similar issues?

2

I have drops on quad9 (Virgin Media) using DoH, but my problem is all the time not just now and then.
Out of interest which server are you connected to ?

kdig @9.9.9.9 TXT id.server.on.quad9.net +https

I have Zero issues with Cloudflare DoH/Adlists on 7.18

Settings…

/ip/dns/export

ip dns
set allow-remote-requests=yes cache-max-ttl=1d cache-size=250000KiB \
    doh-max-concurrent-queries=200 doh-max-server-connections=6 max-concurrent-queries=200 \
    max-concurrent-tcp-sessions=40 use-doh-server=https://cloudflare-dns.com/dns-query \
    verify-doh-cert=yes
/ip dns adlist
add url=https://raw.githubusercontent.com/hagezi/dns-blocklists/main/hosts/pro.txt
/ip dns static
add address=192.168.88.1 comment=defconf name=router.lan type=A
add address=1.1.1.1 name=cloudflare-dns.com type=A
add address=1.0.0.1 name=cloudflare-dns.com type=A
add address=9.9.9.9 disabled=yes name=dns.quad9.net type=A
add address=149.112.112.112 disabled=yes name=dns.quad9.net type=A
3

FYI 7.19beta2 doesn’t solve the problem!

# 2025-02-28 13:37:34 by RouterOS 7.19beta2
# software id =
#
 2025-02-28 13:34:00 dns,error DoH server connection error: resolving error
 2025-02-28 13:34:00 dns,error DoH server connection error: resolving error [ignoring repeated messages]
 2025-02-28 13:36:08 dns,error DoH server connection error: resolving error
 2025-02-28 13:36:08 dns,error DoH server connection error: resolving error [ignoring repeated messages]
 2025-02-28 13:36:31 dns,error DoH server connection error: resolving error
 2025-02-28 13:36:31 dns,error DoH server connection error: resolving error [ignoring repeated messages]
4

I have iformation from Quad9 support, that Mikrotik is using old protocol HTTP/1.1 and that Qoud9 is using new protocol HTTP/2.0. Quad says that the will not support the old protocol soon anymore…