I also got a Solo2 that can't handle subs either. I have tried several images such as Openpli, Vix, Blackhole, Openatv with same result.
Could it be the provider of the IPTV?
Yes, subs is enabled. Sometimes the subs appear but only every 8-9 line. Read something about missing DVB-drivers on older Vu+ models.
Is it possible that's the case? Duo2 is 6 years old and Solo 4K 3 years old.
I have a VU+ Dou2 and is not able to get subtitles on swedish channels, tried several images with no luck.
Dreamboxes handles subtitles from what i read. Is DM900 able to show subtitles?