Next DNS poor browsing performance

I've been using NextDNS for a long time. I configured NextDNS on my Keenetic router. I'm getting pretty poor browsing performance when using it with my Macbook Air M1. I noticed this because this performance issue disappeared when I connected via hotspot. 

Also, i am trying to use diag: https://help.nextdns.io/t/y4hmvcx/report-network-latency-issue

But i am getting error as command output: 

/tmp/nextdns-diag-3483: line 1: Not: command not found

So, I ran diag via my Raspberry Pi 4. Results: 

Testing IPv6 connectivity
  available: false
Fetching https://test.nextdns.io
  Fetch error: Get "https://c4joqakjvm99cnj28jo0.test.nextdns.io/": dial tcp 5.188.168.252:443: i/o timeout
Fetching PoP name for ultra low latency primary IPv4 (ipv4.dns1.nextdns.io)
  edgeuno-ist: 21.707ms
Fetching PoP name for ultra low latency secondary IPv4 (ipv4.dns2.nextdns.io)
  premiumrdp-ist: 22.834ms
Fetching PoP name for anycast primary IPv4 (45.90.28.0)
  edgeuno-ist: 50.941ms
Fetching PoP name for anycast secondary IPv4 (45.90.30.0)
  anexia-vie: 99.245ms
Pinging PoPs
  edgeuno-ist: 20.249ms
  albahost-prn: 172.47ms
  edis-ath: 171.54ms
  edis-buh: 172.966ms
  mvps-ath: 172.677ms
  anexia-buh: 172.582ms
  estnoc-buh: 173ms
  netshop-nic: 172.889ms
  citynet-cai: 174ms
Traceroute for ultra low latency primary IPv4 (185.40.106.78)
    1    192.168.2.1    1ms   1ms   1ms
    2  212.156.201.9   12ms  10ms  10ms
    3   81.212.2.159    5ms   5ms   6ms
    4  81.212.221.30    8ms   8ms   7ms
    5   81.212.26.59   19ms  20ms  20ms
    6                   *     *     *
    7 86.106.122.141   21ms  21ms  21ms
    8 86.106.122.154   21ms  20ms  20ms
    9  185.40.106.78   20ms  21ms  20ms
Traceroute for ultra low latency secondary IPv4 (5.188.168.252)
    1    192.168.2.1    1ms   1ms   2ms
    2  212.156.201.9   13ms  10ms  10ms
    3   81.212.2.159    5ms   5ms   5ms
    4  81.212.221.30    8ms   8ms   8ms
    5   81.212.26.59   19ms  19ms  20ms
    6                   *     *     *
    7 86.106.122.141   33ms  23ms 143ms
    8    31.210.9.65   25ms 144ms  24ms
    9                   *     *     *
   10                   *     *     *
   11                   *     *     *
   12                   *     *     *
   13                   *     *     *
   14                   *     *     *
   15                   *     *     *
   16                   *     *     *
   17                   *     *     *
   18                   *     *     *
   19                   *     *     *
   20                   *     *     *
Traceroute for anycast primary IPv4 (45.90.28.0)
    1    192.168.2.1    1ms   1ms   1ms
    2  212.156.201.9   16ms   9ms   9ms
    3   81.212.71.65    6ms   5ms   5ms
    4  81.212.221.30    8ms   8ms   8ms
    5   81.212.26.59   20ms  20ms  20ms
    6                   *     *     *
    7 86.106.122.141   21ms  20ms  20ms
    8 86.106.122.154   20ms  22ms  20ms
    9 185.40.106.110   20ms  20ms  21ms
   10     45.90.28.0   20ms  20ms  20ms
Traceroute for anycast secondary IPv4 (45.90.30.0)
    1    192.168.2.1    1ms   1ms   1ms
    2  212.156.201.9    7ms   9ms  10ms
    3   81.212.2.159    5ms   5ms   5ms
    4  81.212.221.30    8ms  15ms   9ms
    5 81.212.219.150   21ms  21ms  21ms
    6    81.212.30.7   25ms  25ms  25ms
    7 212.156.139.66   77ms  77ms  79ms
    8   62.115.37.72   79ms  78ms  77ms
    9 62.115.114.110   70ms  50ms  54ms
   10 62.115.114.185   99ms 100ms  99ms
   11  62.115.62.153   51ms  50ms  50ms
   12 144.208.208.133   51ms  51ms  51ms
   13 144.208.208.135   51ms  52ms  51ms
   14     45.90.30.0   57ms  57ms  57ms
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{"error":"0: instance.Test requires property \"Client\"\n"}