I will be traveling from Laos with Lao Airlines, transiting in Bangkok to Colombo with SriLankan Airlines, the upcoming end of September. My flight with Lao Airlines will arrive in Bangkok at 19:40, and my SriLankan Airlines flight leaves Bangkok at 21:50. I will be 2:10 hours in transit.
Will this be enough time for the transit?
Do I still have to pass Immigration & Customs at Bangkok to check in my bags for my other flight, given that it's two different airlines?
I have a European passport.
Assuming this is a single ticket (and based on your description it sounds like one), you'll be fine.
Your bags will be checked through to Colombo, and you do not need to pass through immigration or customs. You may need to visit a transfer desk to pick up your second boarding pass if this cannot be issued in Laos.
Bangkok Suvarnabhumi is a large airport, but it's also all in a single enormous building and even walking the whole length of several kilometers only takes half an hour max, with a little help form the moving walkways. So two hours should be plenty, and even gives you a little buffer if your flight is delayed. Also, since you have a single ticket, you'll be put on the next available flight for free even if you do miss it due to a delay.
