Joining two parts of a sentence

[Anonymous]

In a list of actions that take place one of them reads as follows:

Client attempts to communicate with web server by sending a SYN packet which is temporarily held in XK1 buffer.

(similar to: John posts letter to his friend which is temporarily delayed at post office.)

The sentence needs to be short, clear and concise as its part of a list of comments and the overall message is more important than the detail.

The problem I always have when writing sentences is either I say too much, or I am unable to form and join the clauses in an efficient and logical way (my short term memory is unable to hold my thoughts whilst I try to write it down).

In the first example I use 'which' to join the two clauses and it doesn't sound correct. I've just looked up 'which' and its more suited to determining 'which' item in a list is required.
So I replaced 'which' with 'that' and it still didn't sound write. I looked up 'that', 'which' is described as a Demonstrative Pronoun 'that' substitute nouns when the nouns they replace can be understood from the context.

I'm getting very confused, can you see the hole I am digging myself and offer a suggestion as to how I may simplify my writing.

Many Thanks
Graham

[Mister Micawber]

Either 'which' or 'that'-- both are common, and about as straightforward as you can get.

Or you can delete both it and the verb -- 'a SYN packet temporarily held in XK1 buffer', which is equally clear in this structure.