In a statement, the broadcaster said: "On Saturday 25 September 2021, Channel 4’s channels and on-demand services were significantly affected when the fire suppression system was triggered at Red Bee Media, the company that broadcasts our services. The building was evacuated and no one was injured, but as a result, we were temporarily off-air.
Even though all our channels are now broadcasting again, the problems caused by the incident means we are still experiencing issues with programmes and adverts as well as with audio and video quality. Since the incident we have also continued to have problems with our All 4 service and are not able to offer any programmes with audio description, subtitles or sign language.
So, we would like to apologise for any problems you might still be experiencing as you watch your favourite shows. We want to reassure you that we are doing everything we can to return to a normal service as quickly as possible.
Until then, bear with us if things don’t always go to plan. We are trying our best."