Monthly Archives: December 2017

How not to have a network with the same out-of-syncness as the Egyptian Army Band playing the Marseillaise.

The infamously out-of-sync Egyptian Army Band

We recently helped an office in South Dublin who were having a tumultuous time with their network. They had three offices in the same building all feeding off the same Vodafone broadband line. For all users, the connection worked, but was extremely intermittent. Sometimes the connection would be fine – other times it would start dropping out. Needless to say, these dropouts had a happy knack of coinciding with their project deadlines which made the problem even more frustrating. They were on Vodafone modem # 3 by the time they called us and but were still experiencing problems. (Vodafone’s solution to send out a new modem to business customers every time they are experiencing an internet problem seems like an extremely lazy and expedient approach to customer service). On recommendation of a business associate they called RealClear.

A rogue DHCP server will play havoc with your network . This access point with IP address of 192.168.1.253 was acting as the default gateway causing intermittent internet drop- outs

Within a few minutes of logging into their Vodafone modem-router the problem became immediately apparent. The “default gateway” appeared as a device using the IP address 192.168.1.253 when it should have been 192.168.1.1 (the IP address of their Vodafone modem-router). On any LAN (local area network) it is crucial that the default gateway is set correctly on all devices. To use a simple analogy, the “default gateway” device acts like the conductor of an orchestra, it orchestrates how all network devices work together. It also acts as a DHCP server, which distributes IP addresses to all devices on the network. In this particular case, the default gateway 192.168.1.253 was registered as a TP-Link access point which was located in an upstairs office. This access point was also operating in erroneously “DHCP server” mode. So, to extend the orchestra analogy, this was an orchestra with two conductors and the players (network devices) were more out-of-sync than the Egyptian Army Band giving a rendition of the Marseillaise.

The Solution

The solution was simple. We disabled the DHCP server on the rogue TP-Link access point. We put the device into access point mode and inputted the correct default gateway settings. A 3 month problem solved by a 20 minute fix. Like most problems, it all goes back to accurate diagnosis and sometimes seemingly intractable problems have the simplest solutions.