Or… if you are going to change things, at least don’t break things!
Remember the first time you learned about NAT? Or PAT? Or changing TCP MSS at the router level?
Cool stuff. The network became involved in adjusting, changing, shaping, or translating packet header values as data passed through. These alterations to packet headers were made for several reasons - everything from extending the life of IPv4 address ranges to making header room for WAN acceleration technologies - allowing engineers to keep data flowing in today’s networks at top speed. That is pretty impressive given that the two main data protocols, IP and TCP, are about to turn 40 years old. (Wow!)
These adjustments to header values by the network are very much in use today, which is a great thing - until something goes wrong. At times, the configurations on routers and other network devices that make these adjustments can be either mistyped, misunderstood, miscalculated, or some combination of the three. This can lead to problems in both connectivity and performance of applications, which can appear to lag or break altogether.