LW 5.3.6 should be able to connect without issue. Only issue might be if it had an old connection file. All LW 5 versions suffer same issue that if the connection file is 30 or more days old then LW will delete the file as it opens and then unable to connect.

Get a fresh connection installer for LW from here. If you do not use LW 5.3 very often then perhaps install LimeStart also.

One good thing about LW 5.3.6 is it was a little lighter than the later versions. ie: not quite as over-bloated in size. There were also a couple other good things about 5.3 that were removed in later versions. One of these removals was due to pressure the company was under from their early legal negotiations.

Birdy and I always believed LW 5 should never have been released publicly until at least 5.2. Instead the company used their general LW user community as beta testers for a program that simply was not up to scratch. But even 5.2 was somewhat buggy.