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DNS Failure – Internet Connected but Websites and POS Payments Not Working

R
Written by Rohit Yadav

DNS Failure – Internet Connected but Websites and POS Payments Not Working

Environment: Restaurant Network
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1. Purpose

This SOP explains how to troubleshoot DNS resolution problems in a Pronto network.

This situation happens when:

  • Internet connection is active

  • Devices receive valid IP addresses

  • But websites and POS payment services do not work

  • Ping is working from Router and POS system on IP address but failing on FQDN

Example:

  • POS cannot connect to payment processor

  • Guest Wi-Fi connects but websites do not load

This is typically a DNS resolution issue, not an internet outage.
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2. Scope

This procedure applies to:

  • POS terminals

  • Back-office computers

  • Guest Wi-Fi devices

  • PC61 router

  • PC26 access points

This SOP does NOT apply when:

  • Internet connection is completely down

  • ISP link is disconnected
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3. Typical Symptoms

Staff may report:

  • Internet is connected but websites don’t load.

  • Payment machine cannot process cards.

  • Guest Wi-Fi connects but nothing opens.

  • PCC devices are not HB to PCC portal

Technical indicators:

  • Device receives valid IP

  • Device can ping gateway

  • Device can ping external IP

  • Domain names fail to resolve

Example test result:

Ping 8.8.8.8 → Works
Ping google.com → Fails

This confirms DNS failure.

4. Business Impact

If DNS fails:

  • POS card payments may fail

  • Online ordering may stop

  • POS cloud sync may fail

  • Guest Wi-Fi browsing stops

  • Pronto Devices stops HB to PCC portal

  • Visibility lose and Devices management impacted

Severity: Medium → High

5. Common Root Causes

Most DNS issues in Pronto deployments occur because of:

  • ISP DNS server outage

  • Incorrect DNS configured on PC61 router

  • DHCP distributing wrong DNS server

  • Router DNS service glitch

  • Device DNS cache issue


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6. Tools Available in Pronto

Use PCC → Device → Diagnostics

Available tools:

  • Ping

  • Traceroute

  • DNS Lookup

  • Packet Capture

  • ARP Table

  • Speed Test

  • Wi-Fi Scan

For DNS troubleshooting, mainly use:

  • Ping with IP and FQDN

  • DNS Lookup (Use Gateway IP and 8.8.8.8) If resolution is coming with 8.8.8.8 means ISP DNS allocated by Router is not working
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7. Troubleshooting Procedure

Follow the steps in order.

Step 1 — Test Internet Connectivity

Open:

Diagnostics → Tools → Ping

Run:

Ping 8.8.8.8

Expected result:

  • Replies received

  • Latency displayed

If ping fails:

This is not a DNS issue.

Possible causes:

  • WAN outage

  • ISP problem

Escalate as internet connectivity issue.

Step 2 — Test DNS Resolution

Open:

Diagnostics → DNS Lookup

  • Test on dns lookup in the tools section using gateway IP (Router IP):

google.com

Expected result:

DNS returns IP address.

Example:

142.250.xxx.xxx

  • If DNS lookup fails: Try with 8.8.8.8 as DNS

google.com

Expected result:

DNS returns IP address.

Example:

142.250.xxx.xxx

If DNS lookup passes, this is the issue with DNS server IP allocated by Router.

Example errors:

  • Request timed out

  • Server not found

DNS failure confirmed.

Step 3 — Confirm DNS Issue Using Ping

Run:

Ping google.com

Interpret results:

Test

Result

Meaning

Ping 8.8.8.8 works

Internet OK

Ping google.com fails

DNS issue


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Step 4 — Check Router DNS Configuration

Login to Pronto Cloud Controller.

Check router settings:

Go to network section -> Edit VLAN -> select ISP/ custom DNS

Verify DNS servers.

Recommended configuration for custom DNS, IF ISP allocated DNS if failing.

Primary DNS: 8.8.8.8
Secondary DNS: 1.1.1.1

If DNS fields are blank or incorrect, update them.
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Step 5 — Verify DNS from Client Device

On a Windows computer open CMD:

Run the command ipconfig /all

Check:

DNS Servers

Confirm DNS server matches router configuration.
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8. Resolution Scenarios

Scenario A — ISP DNS Server Down

Solution:

Use public DNS servers.

Example:

8.8.8.8
1.1.1.1

Scenario B — Incorrect DHCP DNS

Fix DHCP configuration so correct DNS is distributed.
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Scenario C — Router DNS Glitch

Restart PC61 router.

This restarts DNS proxy service.

Note: In case of DNS issue on PCC Router causing issue in HB communication, PCC Router will auto fallback to google DNS after waiting 10 to 15 mins, Indicator could be Yellow status LED light on Router
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9. Validation After Fix

Confirm the following:

  • DNS lookup returns valid IP address

  • Websites load normally

  • POS can process test payment

  • Guest Wi-Fi browsing works

  • No DNS timeout errors appear
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10. Preventive Measures

To reduce DNS issues:

  • Configure reliable public DNS

  • Keep router firmware updated

  • Document DNS settings

  • Periodically test DNS resolution

11. Escalation Guidelines

Escalate to ISP if:

  • Public DNS also fails

  • WAN link unstable

  • DNS queries leave network but no response returns

Escalate to Network Engineering if:

  • DNS configuration resets automatically

12. Quick Diagnostic Summary

If websites do not load but internet works:

  1. Ping gateway

  2. Ping 8.8.8.8

  3. Run DNS lookup

  4. Verify DNS configuration

  5. Use public DNS

  6. Test POS payment


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