Probably one field tag is enough

@@ -13 +12,0 @@
-<field>&comp;</field>

https://e-words.jp/w/同時接続数.html

I think this is primarily an abbreviation of 同時接続 following the very common ABCD -> AC pattern. Streamers et al. are sure to be using it.

@@ -12 +12,3 @@
-<xref type="see" seq="2860276">同時接続数</xref>
+<xref type="see" seq="2860277">同時接続</xref>
+<field>&comp;</field>
+<field>&telec;</field>
@@ -14,2 +15,0 @@
-<misc>&net-sl;</misc>
-<gloss>concurrent viewers (i.e. of an internet livestream)</gloss>

Dated 2023, includes 同接 as an abbr of 同時接続数. 
https://e-words.jp/w/同時接続数.html
同時接続数 【concurrent connections】 同接 / 同時接続ユーザー数 / concurrent users

Example graph ranked by concurrent user count: 同接順で上位10配信の最大視聴者数の合計値「トップ10同接」
https://twitter.com/Holo_Data/status/1756589134884286574

Googits(rough comparison):
site:twitter.com　"同時接続数"  6,500
site:twitter.com　"同時接続"　　24,000
site:twitter.com　"同接"       70,000 (abbr is most common online form)
site:twitter.com　"同接数"     2500 (as abbr, far more common without 数)
site:twitter.com　"同接続"　　　500 (effectively does not occur)
site:twitter.com "同接して"   100. Minimal, but anything is する if you believe...

https://blog.atisfyreach.com/heres-how-much-you-should-be-spending-on-twitch-influencer-marketing
ACV stands for “average concurrent viewers”, which is the average number of viewers a creator has during their broadcasts. 

https://www.reddit.com/r/Nijisanji/comments/1az2rpn/solid_insight_from_yahoo_jp/
isn't 同接 viewers (同時接続数, concurrent connections) in this context? I don't know if it means something else in the finance context.
Reply: You are right. It's just that this word is too much of a vtuber/streamer lingo that a regular translator software won’t be able to recognize it

Google "同接ランキング" for a mountain of modern usage examples(ranking of live streamers by concurrent active connections).

I'm here after encountering a failed machine translation in the wild, followed by an explicit discussion of the issue (last ref, reddit).

As in 同接ランキング, the cases where is appears as [net-sl] will be almost exclusively plural. (This is an abbr of 同時接続数, after all. Though in practice 同時接続 will usually end up pluralized as well...)

As slang, "concurrent viewers" seems to be the common English analog, even though this has some wrinkles. The technical distinction is that one viewer can have multiple connections open, while the server software can only track connections(1 user = multiple connections).  On the other hand, when I hear "concurrent viewers", I just assume that the system can't distinguish "actual" viewers from connections anyway.  So this distinction is rather small in practice.

Also, 同接 might reasonably also be considered to be influenced by:
同時接続者	4993
So there is an argument there as well.

I'm fine with a shorter "i.e. of a livestream", or something else, but that may not be friendly to unfamiliar users.