After changing DNS servers internet works half or not at all
Custom DNS (1.1.1.1, 8.8.8.8, or your own filter) is tidy, but one typo or unreachable server takes the whole office offline.
Try this first
- 1Test on a laptop: set DNS back to "automatic" or "obtain via DHCP". Everything works now? Then the custom DNS was the cause.
- 2Check which DNS servers are configured in your router. A typo (8.8.8.8 vs 8.8.8.0) is more common than you think.
- 3Test each DNS server separately: "nslookup google.com 1.1.1.1" returns an answer? Then it works. No answer? Server unreachable.
- 4Always set two DNS servers (primary + secondary). One alone means total outage on a single failure.
When to bring us in
With DNS filtering (Cisco Umbrella, NextDNS, AdGuard, etc.) office apps occasionally hit walls. We tune the policy to what you actually want filtered.
See also
- Wi-Fi drops randomly across the officeFirst rule out whether it is the access points or the internet connection itself. Different fix.
- One room or corner has no or bad Wi-FiNot always "add another AP"; often one is poorly positioned, or there is a metal wall in the way.
- Internet is suddenly slow for everyoneThree suspects: your provider, a colleague soaking the line, or a backup or update kicking in unexpectedly.
None of the above fits?
Describe your situation below. We pass your input plus the steps you already saw to our AI and return tailored next-step advice. If it's too risky to DIY, we'll say so.
Or skip the DIY entirely
Our Managed IT clients do not look these things up. One point of contact, a fixed monthly price, resolved within working hours.