MTU describes the maximum size of a packet on a particular link without fragmentation at that layer. A genuine path issue can affect transfers, but copying an arbitrary smaller value is not a general buffering remedy.
Recognise a specific failure
Some sites or large transfers failing while small requests work can justify further investigation. Similar symptoms have many causes, including firewalls and service faults. Keep a record of the destinations and tests rather than changing several router options at once.
Use documented diagnostics
Follow the operating system and internet provider's guidance for the actual connection type. Different access arrangements can have different requirements. Do not assume that a value posted for another router or tunnel applies to your line.
Restore unsuccessful experiments
If a temporary change does not produce a repeatable improvement, return to the original value. An unnecessarily small MTU can add overhead. Ask the access provider for its required settings when a reproducible path problem remains.
