I recently faced problem of working router and Internet is working on all devices except on my Garuda System .
On Garuda it shows Limited Internet connectivity and the cause is DNS resolution fails , which I confirmed by
ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=53 time=54.4 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=53 time=58.6 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=53 time=56.4 ms
Open Garuda Assistant > Settings > Choose DNS service
and set it to default ,for some reason it does not works and causes intermittent DNS resolution failure .
If this also not fixes your problem chances are it is due to buggy iwlwifi driver in new kernels and I suggest you to install linux-lts and boot with it .