fix: explain transport host rejections #2363

Job	Run time
checks / pre-commit	33s
checks / readme-snippets	14s
checks / test (3.11, lowest-direct, windows-latest)	3m 38s
checks / test (3.10, locked, windows-latest)	2m 42s
checks / test (3.10, locked, ubuntu-latest)	1m 1s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 4s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 11s
checks / test (3.13, locked, windows-latest)	2m 40s
checks / test (3.11, locked, ubuntu-latest)	1m 3s
checks / test (3.10, lowest-direct, windows-latest)	2m 39s
checks / test (3.14, locked, ubuntu-latest)	2m 32s
checks / test (3.14, locked, windows-latest)	3m 34s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 1s
checks / test (3.12, locked, ubuntu-latest)	55s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 6s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 33s
checks / test (3.11, locked, windows-latest)	2m 37s
checks / test (3.12, lowest-direct, windows-latest)	3m 37s
checks / test (3.13, lowest-direct, windows-latest)	2m 47s
checks / test (3.13, locked, ubuntu-latest)	51s
checks / test (3.14, lowest-direct, windows-latest)	2m 53s
checks / test (3.12, locked, windows-latest)	2m 44s
all-green	2s
	42m 57s

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