I have 2 similar boxes farming chia.
Box1 is on 1.1.8.dev0 ( about 1600 plots , cpu 5600x ).
Box2 is on 1.2.0 ( about 2300 plots , cpu 5800x ).
After farming for roughly 6 months,
I got 14 (hit 7 times) on box2 , and 0 from box1.
Would 1.1.8.dev0 be too old to get reward?
Both versions are pretty old. But no idea if there is a downside on the chance to win.
Box 1 is unlucky you could say, but there are many reports of people with similar farm sizes not getting a reward in many months.
Box 2 is very lucky.
It’s not that you have changed the reward addresses on box1 to the wallet of box2 so all wins go there?
If you’re thinking about upgrading versions, do yourself a favor and backup the blockchain and wallet databases before. Upgrading can mess things up and having to sync from scratch on a fresh installation is no fun with today’s blockchain-size…
Do a search on backup/restore of the db’s if you’re not sure.
Yeh, I didn’t touch the reward address of box1.
Thank you for your remind, I am still hesitating of upgrading 
I will start from ‘howto backup db’ if I decide.
Also I don’t think there is much difference between 1.1.8dev0 and 1.2.0.
Since 1.1.7 is the last official release in the pre NFT (pooling) era I think 1.1.8dev0 is just the ‘working name’ of what was a bit later released as 1.2.0. Could be there are a few minor improvements during the final release and maybe some debugging code removed.
What OS are you running on the boxes?
I take it you have separate keys/mnemonics for both?
Have you considered running box1 as a harvester?
Roughly around v1.2.0 (don’t remember which one), there were some issues reported on github Issues page about people with PB size farms not getting any wins. A follow up version cleared that (I think). Again, I don’t really recall exactly which version it was that had those potential issues. So, why not to upgrade that dev version to at least v1.2.0, as that seems to work for you?
Chia officials urged to update to 1.2.11 as it has fixes that combat dust storms