Upgrade lwIP to 2.0.3 or even newer, from 1.4.1

lwIP 1.4.1 (2012.12.17) was the last of 1.x.

+

lwIP 2.0.0 (2016.11.10): 'numerous bugfixes and improvements (including dual-stack IPv6 support)'.

lwIP 2.0.1 (2017.01.10): 'only to fix some bugs since 2.0.0'.

lwIP 2.0.2 (2017.03.13): 'only to fix some bugs since 2.0.1'.

lwIP 2.0.3 (2017.09.16): 'only to fix some bugs since 2.0.2. All users using 2.0.x are strongly suggested to upgrade!'.

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lwIP 2.1.0 (2018.09.26): 'TLS support via the new altcp API ...'.

lwIP 2.1.1 (2018.11.08): 'bugfix-only'.

lwIP 2.1.2 (2018.11.22): 'bugfix-only ... strongly suggested to upgrade!'

lwIP 2.1.3 (2021.11.10): 'bugfix-only'.

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lwIP 2.2.0 (2023.09.25): 'some bugs fixed, and some new features were added (most notably full ACD support)'.