MTU Finder — Path MTU Test

Find the largest packet that actually reaches a host without being fragmented — the path MTU — straight from your phone.

If your VPN keeps stalling, some websites load while others hang forever, or SSH freezes on large output, a wrong MTU is a common cause. This app measures it instead of making you guess.

HOW IT WORKS
Type a host — 8.8.8.8, your router, your VPN endpoint, any name or address — and start the test. The app sends ping packets with the "don't fragment" flag set and narrows in with a binary search, so it finds the exact boundary in about a dozen probes rather than hundreds.

WHAT YOU SEE
• The path MTU in bytes, ready to put into your router or VPN config
• The size being probed at each step, so you can watch the search converge
• The MTU your device reports for each of its own network interfaces — useful for comparing Wi-Fi against mobile data
• Your last five results, so you don't have to write them down

NOTES
• Some hosts drop ICMP entirely. If a test fails, try another target such as 8.8.8.8 or 1.1.1.1.
• The result describes the path from this phone to that host on the network you are on right now. Change networks and it can change.

PRIVACY
• No ads, no analytics, no accounts
• Results are stored on your device and may be included in Android device backups
• The only traffic is the ping probes you ask for

Requires Android 8.0 or later.

Recent changes:
Offline tests now show when the internet connection is unavailable. Reconnect and tap Try again to restart the test.