what the arduino is reading is not what it should be
4.10.1 Controlling character set translationDuring an interactive session, PuTTY receives a stream of 8-bit bytes from the server, and in order to display them on the screen it needs to know what character set to interpret them in.There are a lot of character sets to choose from. The 'Received data assumed to be in which character set' option lets you select one. By default PuTTY will attempt to choose a character set that is right for your locale as reported by Windows; if it gets it wrong, you can select a different one using this control.A few notable character sets are: The ISO-8859 series are all standard character sets that include various accented characters appropriate for different sets of languages. The Win125x series are defined by Microsoft, for similar purposes. In particular Win1252 is almost equivalent to ISO-8859-1, but contains a few extra characters such as matched quotes and the Euro symbol. If you want the old IBM PC character set with block graphics and line-drawing characters, you can select 'CP437'. PuTTY also supports Unicode mode, in which the data coming from the server is interpreted as being in the UTF-8 encoding of Unicode. If you select 'UTF-8' as a character set you can use this mode. Not all server-side applications will support it.If you need support for a numeric code page which is not listed in the drop-down list, such as code page 866, then you can try entering its name manually (CP866 for example) in the list box. If the underlying version of Windows has the appropriate translation table installed, PuTTY will use it.
Change preproc.substitute_unicode from true to false.
If there is only one string you want, I'd figure out what the actual bytes are, and match that byte by byte.
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-7">