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Out of curiosity, I connected my laptop with an ethernet cable to the router and fired up Wireshark to understand and 'visualize' what's going on.

Some packets caught my attention.

I was having some TCP retransmissions from time to time to and from WAN traffic, I don't have meaningful LAN traffic btw.

I started to become worried knowing that I'm having retransmissions, but thinking it's coming from and to the internet it is to be expected from time to time... I guess? Although I find it hard to quantify if it's too much and how much is acceptable.

PS: Just to say it is not about TCP retransmissions with TCP Port numbers reused.

Giacomo1968
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Netu30
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2 Answers2

17

TCP retransmissions are perfectly normal and expected as long as there aren't too many. It should probably be less than 1% of your TCP segments that get retransmitted.

Retransmissions are normal because dropped packets are normal. Dropped packets are actually used as a signal between routers and senders' TCP stacks that network congestion is happening, so the sending TCP stack needs to use its congestion control algorithm to back off its transmission speed for a moment.

Spiff
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A certain amount of Network Retransmission is entirely normal.

You would have to track it to see if increasing or level.

I see this here.

Comm View trace