There are a few things that might be going on here. I have done a lot of dev hiring over the last 10 years in the Bay Area and this is what I've seen:
1. Ageism is very real in the bay area. People see a huge list of experience going back to 1985 and graduation dates in that range and they filter you. It is terrible but true. If you are sending a 5 page resume of experience to win them over, try including only your best and most relevant work from the last 10 years and omit graduation dates, etc. See how that works to at least get to the first interview.
2. In addition to the conscious ageism, there is a lot of unconscious stuff people do that also excludes older devs. Even if someone doesn't include dates, I can tell almost immediately they are from another engineering culture (either physical or temporal aliens). There are a lot of little cues that people might interpret as you not being "a good fit", "old school", or "enterprise-y". If you are friends with any hip 30-35 year old devs, have them review for cues like that and squash them. Quite possibly you'll also find there are real holes in your resume or way you are presenting yourself.
3. On that note, have that same hip dev friend cross reference his version of what tech is hot with your expertise. You might be a great dev in 100 ways but your attachment to php (haha, jk php lovers!) will peg you as "old school". If you really don't have experience in any of that hot tech, "I can pick stuff up" only goes so far especially if people are already wondering because of your age. Build something real (!"I did a tutorial or toy app and it seems cool") using one of those hot tools and put it on your resume.
Everything above applies to LinkedIn or Github profiles too, not just your resume since people will immediately check those also. Of course, when you get to a first interview, you might still get filtered but at least you'll have a shot.
I know it is pretty callous to just try and work around ageism as I'm recommending but sadly I think this is the hurdle older devs need to tackle to get to the first interview. I see older guys not finding work all the time.
To be clear, this perspective isn't coming from someone in their 20s. I'm 45 and am already seeing these harsh realities. I feel like I get to see both sides of it since I own my own company and I've been immersed in the 25-35 year old hipster dev culture all along which helps me to stay very current in lingo, trends, appeal. Because we see it all the time, we're very careful to avoid this ageism trap in our hiring by moving people forward using very well defined criteria, not subjective "I got a good feeling about him" type heuristics that might lead us to filter really great devs because of our unconscious biases.