emailsender with W5100 crash

Hello, it has been a long time since I had any questions and / or problems! I have a program which sends emails (among other things because it is a connected hive) and which works very well with a W5500 Ethernet Shield but not with a w5100 shield .... With the W5100 after successfully sending 2 emails the shield crashes ... While with the W5500 (from KeyesStudio) no problem I can send as many emails as I want ... Has anyone ever had this problem and know how to fix it? Thank you PS: it is exactly the same program except that I replace the W5500 by a W5100! All with an Arduino Mega and Renzo's super libraries!