对 DNS 服务器使用降级功能集 (UDP)

Question

我在有线连接上遇到 DNS 问题。由于某种原因，尽管我可以 ping 通，但 DNS 无法正常工作。一些日志：

systemd[1]: Started Network Name Resolution.
systemd-resolved[1060]: Using degraded feature set (UDP) for DNS server 8.8.8.8.
systemd-resolved[1060]: Using degraded feature set (TCP) for DNS server 8.8.8.8.

$ systemd-resolve --status
Global
       LLMNR setting: no                  
MulticastDNS setting: no                  
  DNSOverTLS setting: no                  
      DNSSEC setting: no                  
    DNSSEC supported: no                  
          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 3 (wlp0s20f3)
      Current Scopes: none
DefaultRoute setting: no  
       LLMNR setting: yes 
MulticastDNS setting: no  
  DNSOverTLS setting: no  
      DNSSEC setting: no  
    DNSSEC supported: no  
    
Link 2 (enp2s0)
      Current Scopes: DNS    
DefaultRoute setting: yes    
       LLMNR setting: yes    
MulticastDNS setting: no     
  DNSOverTLS setting: no     
      DNSSEC setting: no     
    DNSSEC supported: no     
  Current DNS Server: 8.8.8.8
         DNS Servers: 8.8.8.8
          DNS Domain: ~.  

resolv.conf 指向/run/systemd/resolve/resolv.conf：

lrwxrwxrwx 1 root root 32 Jan 13 10:43 /etc/resolv.conf -> /run/systemd/resolve/resolv.conf

并包含：

nameserver 8.8.8.8

另外，wifi下也可以。我该如何解决这个问题？