cookies not working after site migration

Hi everyone
We recently migrated our site to new hosts (still with linux), and am now
finding that it is not picking up client cookies.
I only set the name of the cookie, the value (user_id) and expiry date.
The domain name is the same and the name, value and expiry date of the
cookies have not changed, but on the third line of the cookie file there is
a 4-digit number
which before was 1024 and on the new site is now always set to 1536.
Anyone know what could be causing this?


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Regards
Robert Franks