Rockpro64 Headless Server Reliably Becomes Unresponsive

[mknawabi]

It sounds exactly like a DNS outage. What are the contents of /etc/resolv.conf (which specifies your DNS nameservers) ?

Thanks for your response. Command outputs are below.

cat /etc/resolv.conf:

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
# 127.0.0.53 is the systemd-resolved stub resolver.
# run "systemd-resolve --status" to see details about the actual nameservers.

nameserver 127.0.0.53

systemd-resolve --status:

Global
          DNSSEC NTA: 10.in-addr.arpa
                      16.172.in-addr.arpa
                      168.192.in-addr.arpa
                      17.172.in-addr.arpa
                      18.172.in-addr.arpa
                      19.172.in-addr.arpa
                      20.172.in-addr.arpa
                      21.172.in-addr.arpa
                      22.172.in-addr.arpa
                      23.172.in-addr.arpa
                      24.172.in-addr.arpa
                      25.172.in-addr.arpa
                      26.172.in-addr.arpa
                      27.172.in-addr.arpa
                      28.172.in-addr.arpa
                      29.172.in-addr.arpa
                      30.172.in-addr.arpa
                      31.172.in-addr.arpa
                      corp
                      d.f.ip6.arpa
                      home
                      internal
                      intranet
                      lan
                      local
                      private
                      test

Link 2 (eth0)
      Current Scopes: DNS
       LLMNR setting: yes
MulticastDNS setting: no
      DNSSEC setting: no
    DNSSEC supported: no
         DNS Servers: 1.1.1.1
                      192.168.0.1

The DNS is coming from my router's DHCP server, which was previously relying on 8.8.8.8, but I changed it in hopes that it would solve the issue. It did not.

If you have dig installed, you can use dig @nameserver google.com to specify the name server to use for a lookup. That way, you can run a DNS lookup against 127.0.0.53 (the systemd local resolver), and the IP of your router. You can also use dig @8.8.8.8 google.com to use google's DNS servers to look up google.com. 

This way you check your local system, the home network router, and then you finally can test internet connectivity + name server lookups against a well-known working DNS server